Measures of central Tendency

173
Measures Of Central Tendency Quantitative Aptitude & Business Statistics

description

Calculus

Transcript of Measures of central Tendency

  • Measures Of Central Tendency

    Quantitative Aptitude & Business Statistics

  • Quantitative aptitude & Business Statistics: Measures Of Central

    2

    Statistics in Plural Sense as Statistical data.

    Statistics in Plural Sense refers to numerical data of any phenomena placed in relation to each other.

    For example ,numerical data relating to population ,production, price level, national income, crimes, literacy ,unemployment ,houses etc.,

    Statistical in Singular Scene as Statistical method.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    3

    According to Prof.Horace Secrist:

    By Statistics we mean aggregate of facts affected to marked extend by multiplicity of causes numerically expressed, enumerated or estimated according to reasonable standard of accuracy ,collected in a systematic manner for a pre determined purpose and placed in relation to each other .

  • Quantitative aptitude & Business Statistics: Measures Of Central

    4

    Measures of Central Tendency

  • Quantitative aptitude & Business Statistics: Measures Of Central

    5

    Def:Measures of Central Tendency A single expression

    representing the whole group,is selected which may convey a fairly adequate idea about the whole group.

    This single expression is

    known as average.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    6

    Averages are central part of distribution and, therefore ,they are also called measures of central tendency.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    7

    Types of Measures central tendency:

    There are five types ,namely 1.Arithmetic Mean (A.M) 2.Median 3.Mode 4.Geometric Mean (G.M) 5.Harmonic Mean (H.M)

  • Quantitative aptitude & Business Statistics: Measures Of Central

    8

    Features of a good average 1.It should be rigidly defined 2.It should be easy to

    understand and easy to calculate

    3.It should be based on all the observations of the data

  • Quantitative aptitude & Business Statistics: Measures Of Central

    9

    4.It should be easily subjected to further mathematical calculations

    5.It should be least affected by fluctuations of sampling

  • Quantitative aptitude & Business Statistics: Measures Of Central

    10

    Arithmetic Mean (A.M) The most commonly used measure of central tendency. When people ask about the average" of a group of scores, they usually are referring to the mean.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    11

    The arithmetic mean is simply dividing the sum of variables by the total number of observations.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    12

    Arithmetic Mean for raw data is given by

    n

    x

    nX

    n

    ii

    xxxx n=++++ == 1......321

  • Quantitative aptitude & Business Statistics: Measures Of Central

    13

    Find mean for the data 17,16,21,18,13,16,12 and 11

  • Quantitative aptitude & Business Statistics: Measures Of Central

    14

    Arithmetic Mean for Discrete Series

    =

    =++++ =++++

    = n

    ii

    n

    iii

    n

    xfxfxfxf

    f

    xf

    ffffX nn

    1

    1

    321

    ......

    ....332211

  • Quantitative aptitude & Business Statistics: Measures Of Central

    15

    Arithmetic Mean for Continuous Series

    CN

    fdAX +=

  • Quantitative aptitude & Business Statistics: Measures Of Central

    16

    Calculation of Arithmetic mean in case of Continuous Series

    Marks 0-10

    10-20

    20-30

    30-40

    40-50

    50-60

    No. of Students

    10 20 30 50 40 30

    From the following data calculate Arithmetic mean

  • Quantitative aptitude & Business Statistics: Measures Of Central

    17

    Marks Mid values

    (X)

    No.of Students

    (f)

    d= X-45 10

    f.d

    0-10 5 10 -4 -40 10-20 15 20 -3 -60 20-30 25 30 -2 -60 30-40 35 50 -1 -50

  • Quantitative aptitude & Business Statistics: Measures Of Central

    18

    Marks Mid values

    (X)

    No.of Students

    (f)

    d= X-45 10

    f.d

    40-50 45 40 0 0 50-60 55 30 1 30

    N=180 fd=-180

  • Quantitative aptitude & Business Statistics: Measures Of Central

    19

    Solution

    Let us take assumed mean =45

    Calculation from assumed mean

    Mean =

    35180

    10*18045x

    =

    +=+=

    CN

    fdA

  • Quantitative aptitude & Business Statistics: Measures Of Central

    20

    Calculation Of Arithmetic Mean in case of Less than series

    Marks less than /up to

    10 20 30 40 50 60

    No. of students

    10 30 60 110 150 180

  • Quantitative aptitude & Business Statistics: Measures Of Central

    21

    Solution: Let us first convert Less than series into continuous series as follows

    Marks 0-10 10-20

    20-30

    30-40

    40-50

    50-60

    No. of students

    10 20 30 50 40 30 180-150=30

  • Quantitative aptitude & Business Statistics: Measures Of Central

    22

    Calculation Of Arithmetic Mean in case of more than series

    Marks more than

    0 10 20 30 40 50 60

    No. of students

    180 170 150

    120 70 30 0

  • Quantitative aptitude & Business Statistics: Measures Of Central

    23

    Solution: Let us first convert More than series into continuous series as follows

    Marks 0-10 10-20

    20-30

    30-40

    40-50 50-60

    No. of students

    10 20 30 50 40 30

    180-170=10 170-150=20

    70-30=40

    30-0=30

  • Quantitative aptitude & Business Statistics: Measures Of Central

    24

    Calculation of Arithmetic Mean in case of Inclusive series

    From the following data ,calculate Arithmetic Mean

    Marks 1-10 11-20 21-

    30 31-40

    41-50

    51-60

    No. of Students

    10

    20 30 50 40 30

  • Quantitative aptitude & Business Statistics: Measures Of Central

    25

    Solution

    Let us take assumed mean =45.5

    Calculation from assumed mean

    Mean = 35

    18010*18045x

    =

    +=+=

    CN

    fdA

  • Quantitative aptitude & Business Statistics: Measures Of Central

    26

    Marks Mid values

    No.of Students

    d=X-45.5 10

    f.d

    0.5-10.5 5.5 10 -4 -40 10.5-20.5 15.5 20 -3 -60 20.5-30.5 25.5 30 -2 -60 30.5-40.5 35.5 50 -1 -50 40.5-50.5 45.5 40 0 0 50.5-60.5 55.5 30 1 30

    N=180 fd= -180

  • Quantitative aptitude & Business Statistics: Measures Of Central

    27

    Calculation of Arithmetic Mean in case of continuous exclusive series when class intervals are unequal

    From the following data ,calculate Arithmetic Mean

    Marks 0-10 10-30 30-40 40-50 50-60

    No. of Students

    10

    60 50 40 20

  • Quantitative aptitude & Business Statistics: Measures Of Central

    28

    Since class intervals are unequal, frequencies have been adjusted to make the class intervals equal on the assumption that they are equally distributed throughout the class

    Let us take assumed mean =45

  • Quantitative aptitude & Business Statistics: Measures Of Central

    29

    Calculation of Deviations from assumed mean

    Mean=

    778.32180

    1022045x

    =

    +=+=

    XCN

    fdA

  • Quantitative aptitude & Business Statistics: Measures Of Central

    30

    Marks Mid values

    No. of Students

    d= X-45.5 10

    f.d

    0-10 5 10 -4 -40 10-20 15 30 -3 -90 20-30 25 30 -2 -60 30-40 35 50 -1 -50 40-50 45 40 0 0 50-60 55 20 1 30

    N=180 fd=-220

  • Quantitative aptitude & Business Statistics: Measures Of Central

    31

    Combined Arithmetic Mean (A.M)

    An average daily wages of 10 workers in a factory A is Rs.30 and an average daily wages of 20 workers in a factory B is Rs.15.Find the average daily wages of all the workers of both the factories.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    32

    Solution

    Step 1;N1=10 N2=20

    Step2:

    =20

    15;30 21 == XX

    21

    221112 NN

    XNXNX++

    =

  • Quantitative aptitude & Business Statistics: Measures Of Central

    33

    Weighted Arithmetic Mean

    The term weight stands for the relative importance of the different items of the series. Weighted Arithmetic Mean refers to the Arithmetic Mean calculated after assigning weights to different values of variable. It is suitable where the relative importance of different items of variable is not same

  • Quantitative aptitude & Business Statistics: Measures Of Central

    34

    Weighted Arithmetic Mean is specially useful in problems relating to

    1)Construction of Index numbers. 2)Standardised birth and death rates

  • Quantitative aptitude & Business Statistics: Measures Of Central

    35

    Weighted Arithmetic Mean is given by

    = W

    XWX w

    .

  • Quantitative aptitude & Business Statistics: Measures Of Central

    36

    Mathematical Properties of Arithmetic Mean

    1.The Sum of the deviations of the items from arithmetic mean is always Zero. i.e.

    2.The sum of squared deviations of the items from arithmetic mean is minimum or the least

    ( ) 0= XX

    ( ) 02 XX

  • Quantitative aptitude & Business Statistics: Measures Of Central

    37

    3.The formula of Arithmetic

    mean can be extended to

    compute the combined

    average of two or more

    related series

  • Quantitative aptitude & Business Statistics: Measures Of Central

    38

    4.If each of the values of a

    variable X is increased or decreased by some constant C, the arithmetic mean also increased or decreased by C .

  • Quantitative aptitude & Business Statistics: Measures Of Central

    39

    Similarly When the value of the variable X are multiplied by constant say k,arithmetic mean also multiplied the same quantity k .

  • Quantitative aptitude & Business Statistics: Measures Of Central

    40

    When the values of variable are divided by a constant say d ,the arithmetic mean also divided by same quantity

  • Quantitative aptitude & Business Statistics: Measures Of Central

    41

    Merits Of Arithmetic Mean

    1.Its easy to understand and easy to calculate.

    2.It is based on all the items of the samples.

    3.It is rigidly defined by a mathematical formula so that the same answer is derived by every one who computes it.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    42

    4.It is capable for further algebraic treatment so that its utility is enhanced

  • Quantitative aptitude & Business Statistics: Measures Of Central

    43

    6.The formula of arithmetic mean can be extended to compute the combined average of two or more related series.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    44

    7.It has sampling stability .It is least affected by sampling fluctuations

  • Quantitative aptitude & Business Statistics: Measures Of Central

    45

    Limitations of Arithmetic Mean

    1.Affected by extreme values i.e . Very small or very big values in the data unduly affect the value of mean because it is based on all the items of the series.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    46

    2.Mean is not useful for studying the qualitative phenomenon.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    47

    Median

    The middle score of the distribution when all the scores have been ranked.

    If there are an even number of scores, the median is the average of the two middle scores.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    48

    In an ordered array, the median is the middle number If n or N is odd, the median is the

    middle number If n or N is even, the median is the

    average of the two middle numbers

  • Quantitative aptitude & Business Statistics: Measures Of Central

    49

    Potential Problem with Means

    Mean

    Mean

    Median

    Median

  • Quantitative aptitude & Business Statistics: Measures Of Central

    50

    Median

    0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 12 14

    Median = 5 Median = 5

  • Quantitative aptitude & Business Statistics: Measures Of Central

    51

    Median for raw data

    When given observation are even First arrange the items in ascending

    order then

    Median (M)=Average of Item

    21

    2+

    +=NN

  • Quantitative aptitude & Business Statistics: Measures Of Central

    52

    Find the Median for the raw data

    25,55,5,45,15 and 35 Solution ;Arrange the items 5,15,25,35,45,55,here N=6 Median =Average of 3rd and 4th

    item=30

  • Quantitative aptitude & Business Statistics: Measures Of Central

    53

    Median for raw data

    When given observation are odd First arrange the items in ascending

    order then

    Median (M)=Size of Item

    21+

    =N

  • Quantitative aptitude & Business Statistics: Measures Of Central

    54

    Median for continuous series

    cf

    mN

    LM

    += 2

    Where M= Median; L=Lower limit of the Median Class,m=Cumulative frequency above median class f=Frequency of the median class N=Sum of frequencies

  • Quantitative aptitude & Business Statistics: Measures Of Central

    55

    Quartiles

    The values of variate that divides the series or the series or the distribution into four equal parts are known as Quartiles .

  • Quantitative aptitude & Business Statistics: Measures Of Central

    56

    The first Quartile (Q1),known as a lower Quartile is the value of variate below which 25% of the observations.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    57

    The Second Quartile known as middle Quartile(Q2)known as middle Quartile or median ,the value of variates below which 50% of the observations

  • Quantitative aptitude & Business Statistics: Measures Of Central

    58

    The Third Quartile known as Upper Quartile(Q3)known as middle Quartile or median ,the value of variates below which 75 % of the observations.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    59

    thNSizeQ4

    11

    += Item

    thNSizeQ4

    )1(33

    += Item

  • Quantitative aptitude & Business Statistics: Measures Of Central

    60

    Octiles

    The values of variate that divides the series or the distribution into eight equal parts are known as Octiles .

    Each octile contains 12.5% of the total number of observations .

  • Quantitative aptitude & Business Statistics: Measures Of Central

    61

    Since seven points are required to divide the data into 8 equal parts ,we have 7 octiles.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    62

    thNjSizeOj 8)1( +

    = Item

    thNSizeO8

    )1(44

    += Item

  • Quantitative aptitude & Business Statistics: Measures Of Central

    63

    Deciles

    The values of variate that divides the series or the distribution into Ten equal parts are known as Deciles .

    Each Decile contains 10% of the total number of observations .

  • Quantitative aptitude & Business Statistics: Measures Of Central

    64

    Since 9 points are required to divide the data into 10 equal parts ,we have 9 deciles(D1 to D9)

  • Quantitative aptitude & Business Statistics: Measures Of Central

    65

    thNjSizeDj 10)1( +

    = Item

    thNSizeD10

    )1(55

    += Item

  • Quantitative aptitude & Business Statistics: Measures Of Central

    66

    Percentiles The values of variate that divides

    the series or the distribution into hundred equal parts are known as Percentiles .

    Each percentile contains 10% of the total number of observations .

    Since 99 points are required to divide the data into 10 equal parts ,we have 99 deciles(p1 to p99)

  • Quantitative aptitude & Business Statistics: Measures Of Central

    67

    thNjSizePj 100)1( +

    = Item

    thNSizep100

    )1(5050

    += Item

  • Quantitative aptitude & Business Statistics: Measures Of Central

    68

    Relation Ship Between Partition Values 1.Q1=O2=P25 value of variate which

    exactly 25% of the total number of observations

    2.Q2=D5=P50,value of variate which exactly 50% of the total number of observations.

    3. Q3=O6=P75,value of variate which exactly 75% of the total number of observations

  • Quantitative aptitude & Business Statistics: Measures Of Central

    69

    Calculation of Median in case of Continuous Series

    Marks 0-10 10-20 20-30 30-40 40-50 50-60

    No. of Students

    10 20 30 50 40 30

    From the following data calculate Median

  • Quantitative aptitude & Business Statistics: Measures Of Central

    70

    Marks No. of Students

    (f)

    Cumulative Frequencies

    (c.f.) 0-10 10 10 10-20 20 30 20-30 30 60 30-40 50 110 40-50 40 150 50-60 30 180

    N=180

  • Quantitative aptitude & Business Statistics: Measures Of Central

    71

    Calculate size of N/2

    902

    1802

    ==N

  • Quantitative aptitude & Business Statistics: Measures Of Central

    72

    1050

    602

    180

    30

    +=M

    36630 =+=M

  • Quantitative aptitude & Business Statistics: Measures Of Central

    73

    Merits of Median 1.Median is not affected by

    extreme values . 2.It is more suitable average

    for dealing with qualitative data ie.where ranks are given.

    3.It can be determined by graphically.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    74

    Limitations of Median 1.It is not based all the items of

    the series . 2.It is not capable of algebraic

    treatment .Its formula can not be extended to calculate combined median of two or more related groups.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    75

    0 X

    Y

    M

    Less than Cumulative curve

    More than Cumulative Curve

    Median By Graph

    Q3 Q1 CI

    Frequency N/2

    3N/4

    N/4

  • Quantitative aptitude & Business Statistics: Measures Of Central

    76

    Mode A measure of central tendency Value that occurs most often Not affected by extreme values Used for either numerical or

    categorical data There may be no mode or several

    modes

    0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

    Mode = 9

    0 1 2 3 4 5 6

    No Mode

  • Quantitative aptitude & Business Statistics: Measures Of Central

    77

    Mode The most frequent score in the

    distribution. A distribution where a single

    score is most frequent has one mode and is called unimodal.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    78

    A distribution that consists of only one of each score has n modes.

    When there are ties for the most frequent score, the distribution is bimodal if two scores tie or multimodal if more than two scores tie.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    79

    Calculate the mode from the following data of marks obtained by 10 students.

    20,30,31,32,25,25,30,31,30,32

    Mode (Z)=30

  • Quantitative aptitude & Business Statistics: Measures Of Central

    80

    Mode for Continuous Series

    cfff

    ffLZ

    +=

    201

    01

    2Where Z= Mode ;L=Lower limit of the Mode Class f0 =frequency of the pre modal class f1=frequency of the modal class f2=frequency of the post modal class C=Class interval of Modal Class

  • Quantitative aptitude & Business Statistics: Measures Of Central

    81

    Calculation of Mode :Continuous Series

    Marks 0-10

    10-20

    20-30

    30-40

    40-50

    50-60

    No. of Students

    10 20 30 50 40 30

    From the following data calculate Mode

  • Quantitative aptitude & Business Statistics: Measures Of Central

    82

    Marks No. of Students

    (f) 0-10 10 10-20 20 20-30 30 30-40 50 f1 40-50 40 50-60 30

    N=180

    f0

    f2

  • Quantitative aptitude & Business Statistics: Measures Of Central

    83

    667.36667.630

    104030502

    605030

    2 20101

    =+=

    +=

    +=

    Z

    cfff

    ffLZ

  • Quantitative aptitude & Business Statistics: Measures Of Central

    84

    x 0

    Y

    Z 10 20 30 40 50 60

    10

    20

    30

    40

    50

    Calculation Mode Graphically

  • Quantitative aptitude & Business Statistics: Measures Of Central

    85

    Relationship between Mean, Median and Mode

    The distance between Mean and Median is about one third of distance between the mean and the mode.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    86

    Karl Pearson has expressed the relationship as follows. Mean Mode=(Mean-Median)/3 Mean-Median=3(Mean-Mode)

    Mode =3Median-2Mean Mean=(3Median-Mode)/2

  • Quantitative aptitude & Business Statistics: Measures Of Central

    87

    Example

    For a moderately skewed distribution of marks in statistics for a group of 200 students ,the mean mark and median mark were found to be 55.60 and 52.40.what is the modal mark?

  • Quantitative aptitude & Business Statistics: Measures Of Central

    88

    Solution

    Since in this case mean=55.60and median =52.40 applying ,we get

    Mode=3median -2Mean =3(52.40)-2(55.60) Mode =46

  • Quantitative aptitude & Business Statistics: Measures Of Central

    89

    Example

    If Y=2+1.50X and mode of X is 15 ,What is mode of Y

    Solution Y m=2+1.50*15=24.50

  • Quantitative aptitude & Business Statistics: Measures Of Central

    90

    Merits of Mode

    1.Mode is the only suitable average e.g. ,modal size of garments, shoes.,etc

    2.It is not affected by extreme values.

    3.Its value can be determined graphically.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    91

    Limitations of Mode

    1.In case of bimodal /multi modal series ,mode cannot be determined.

    2.It is not capable for further algebraic treatment, combined mode of two or more series cannot be determined.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    92

    3.It is not based on all the items of the series

    4.Its value is significantly affected by the size of the class intervals

  • Quantitative aptitude & Business Statistics: Measures Of Central

    93

    Geometric mean

    nn

    ii

    nniG

    x

    xxxxx/1

    1

    21

    =

    =

    =

  • Quantitative aptitude & Business Statistics: Measures Of Central

    94

    Take the logarithms of each item of variable and obtain their total i.e log X

    Calculate G M as follows

    =

    nX

    AntiMGlog

    log.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    95

    Computation of G.M -Discrete Series Take the logarithms of each item of

    variable and multiply with the respective frequencies obtain their total

    i.e f .log X Calculate G M as follows

    =

    NXf

    AntiMGlog.

    log.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    96

    Merits of Geometric Mean

    1.It is based on all items of the series .

    2 It is rigidly defined 3.It is capable for algebraic

    treatment.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    97

    4.It is useful for averaging ratios and percentages rates are increase or decrease

  • Quantitative aptitude & Business Statistics: Measures Of Central

    98

    Limitations of Geometric Mean

    1.Its difficult to understand and calculate.

    2.It cannot be computed when there are both negative and positive values in a series

  • Quantitative aptitude & Business Statistics: Measures Of Central

    99

    3.It is biased for small values as it gives more weight to small values .

  • Quantitative aptitude & Business Statistics: Measures Of Central

    100

    Calculation of G.M :Individual Series

    From the following data calculate Geometric Mean Roll No 1 2 3 4 5 6

    Marks 5 15 25 35 45 55

  • Quantitative aptitude & Business Statistics: Measures Of Central

    101

    Computation of G.M :Individual Series

    X log X 5 0.6990 15 1.1761 25 1.3979 35 1.5441 45 1.6532 55 1.7404

    log X=8.2107

  • Quantitative aptitude & Business Statistics: Measures Of Central

    102

    36.23)3685.1log(

    62107.8

    loglog.

    ==

    =

    =

    Anti

    Al

    nX

    AntiMG

  • Quantitative aptitude & Business Statistics: Measures Of Central

    103

    Find the average rate of increase population which in the first decade has increased by 10% ,in the second decade by 20% and third by 30%

  • Quantitative aptitude & Business Statistics: Measures Of Central

    104

    Decade % rise Population at the end of the decade

    logx

    1 2 3

    10 20 30

    110 120 130

    2.0414 2.0792 2.1139

    log X=6.2345

  • Quantitative aptitude & Business Statistics: Measures Of Central

    105

    8.119)0782.2log(

    2345.6

    loglog.

    ==

    =

    =

    Anti

    Al

    nX

    AntiMG

    Average Rate of increase in Population is 19.8%

  • Quantitative aptitude & Business Statistics: Measures Of Central

    106

    Weighted Geometric Mean

    =

    wXw

    AntiMGlog.

    log.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    107

    Harmonic Mean (H.M)

    Harmonic Mean of various items of a series is the reciprocal of the arithmetic mean of their reciprocal .Symbolically,

    nXXXX

    NMH1.......111

    .

    321

    ++++=

  • Quantitative aptitude & Business Statistics: Measures Of Central

    108

    Where X1,X2,X3.X n refer to the value of various series.

    N= total no. of series

  • Quantitative aptitude & Business Statistics: Measures Of Central

    109

    Merits of Harmonic Mean

    1.It is based on all items of the series .

    2 It is rigidly defined 3.It is capable for algebraic

    treatment.

  • Quantitative aptitude & Business Statistics: Measures Of Central

    110

    4.It is useful for averaging measuring the time ,Speed etc

  • Quantitative aptitude & Business Statistics: Measures Of Central

    111

    Limitations of Harmonic Mean

    1.Its difficult to understand and calculate.

    2.It cannot be computed when one or more items are zero

  • Quantitative aptitude & Business Statistics: Measures Of Central

    112

    3.It gives more weight to smallest values . Hence it is not suitable for analyzing economic data .

  • Quantitative aptitude & Business Statistics: Measures Of Central

    113

    Calculation of H.M :Individual Series

    From the following data calculate Harmonic Mean Roll No

    1 2 3 4 5 6

    Marks

    5 15 25 35 45 55

  • Quantitative aptitude & Business Statistics: Measures Of Central

    114

    Computation of H.M :Individual Series

    X l/x 5 0.2000

    15 0.0666 25 0.0400 35 0.0286 45 0.0222 55 0.0182

    (1/x)=0.3756

  • Quantitative aptitude & Business Statistics: Measures Of Central

    115

    9744.153576.06

    11

    =

    =

    = =

    n

    ii

    H

    x

    nx

  • Quantitative aptitude & Business Statistics: Measures Of Central

    116

    Compute AM ,GM and HM for the numbers 6,8,12,36

    AM=(6+81+12++36)/4=15.50 GM=(6.8.12.36)1/4=12

    H.M=9.93

    361

    121

    81

    61

    4.+++

    =MH

  • Quantitative aptitude & Business Statistics: Measures Of Central

    117

    Weighted Harmonic Mean

    =

    )(i

    i

    i

    Xww

    HM

  • Quantitative aptitude & Business Statistics: Measures Of Central

    118

    Find the weighted AM and HM of first n natural numbers ,the weights being equal to the squares of the Corresponding numbers.

    X 1 2 3 n

    W 12 22 32 ..n2

  • Quantitative aptitude & Business Statistics: Measures Of Central

    119

    Weighted =

    WiXiWi

    AM.

    )12(2)1(3

    ++

    =nnn

    ++

    +

    =

    ++++

    ++++

    6)12)(1(

    4)1(.....321.....321

    22

    2222

    3333

    nnn

    nnnn

  • Quantitative aptitude & Business Statistics: Measures Of Central

    120

    =

    )(i

    i

    i

    Xww

    HM

    312

    2)1(

    6)12)(1(

    .....321.....321 23222

    +=

    +

    ++

    =

    ++++

    ++++

    n

    nn

    nnnnn

  • Quantitative aptitude & Business Statistics: Measures Of Central

    121

    The AM and GM of two observations are 5 and 4 respectively ,Find the two observations.

    Solution : Let the Two numbers are a and b given

    ( a+b)/2=10 ;a + b=10 GM=4 ab=16 (a-b)2=(a+b)2-4ab=100-64=36

    a-b=6 a=8 and b=2

  • Quantitative aptitude & Business Statistics: Measures Of Central

    122

    The relationship between AM ,GM and HM

    G2=A.H

  • Quantitative aptitude & Business Statistics: Measures Of Central

    123

    1.The empirical relationship among mean, median and mode is ______

    (a) mode=2median3mean (b) mode=3median-2mean (c) mode=3mean-2median (d) mode=2mean-3median

  • Quantitative aptitude & Business Statistics: Measures Of Central

    124

    1. The empirical relationship among mean, median and mode is ______

    (a) mode=2median3mean (b) mode=3median-2mean (c) mode=3mean-2median (d) mode=2mean-3median

  • Quantitative aptitude & Business Statistics: Measures Of Central

    125

    2. In a asymmetrical distribution ____

    (a) AM = GM = HM (b) AM

  • Quantitative aptitude & Business Statistics: Measures Of Central

    126

    2. In a asymmetrical distribution ____

    (a) AM = GM = HM (b) AM

  • Quantitative aptitude & Business Statistics: Measures Of Central

    127

    3. The points of intersection of the less than and more than ogive corresponds to ___

    (a) mean (b) mode (c) median (d) all of above

  • Quantitative aptitude & Business Statistics: Measures Of Central

    128

    .3. The points of intersection of the less than and more than ogive corresponds to ___

    (a) mean (b) mode (c) median (d) all of above

  • Quantitative aptitude & Business Statistics: Measures Of Central

    129

    4. Pooled mean is also called

    (a) mean (b) geometric mean (c) grouped mean (d) none of these

  • Quantitative aptitude & Business Statistics: Measures Of Central

    130

    4. Pooled mean is also called

    (a) mean (b) geometric mean (c) grouped mean (d) none of these

  • Quantitative aptitude & Business Statistics: Measures Of Central

    131

    5. Relation between mean, median and mode is

    (a) meanmode=2(mean-median) (b) meanmedian=3(meanmode) (c) meanmedian=2(mean

    mode (d) meanmode=3(meanmedian)

  • Quantitative aptitude & Business Statistics: Measures Of Central

    132

    5. Relation between mean, median and mode is

    (a) meanmode=2(mean-median) (b) meanmedian=3(meanmode) (c) meanmedian=2(mean

    mode (d) meanmode=3(meanmedian)

  • Quantitative aptitude & Business Statistics: Measures Of Central

    133

    6. The geometric mean of 9, 81, 729 is _____

    (a) 9 (b) 27 (c) 81 (d) none of these

  • Quantitative aptitude & Business Statistics: Measures Of Central

    134

    6. The geometric mean of 9, 81, 729 is _____

    (a) 9 (b) 27 (c) 81 (d) none of these

  • Quantitative aptitude & Business Statistics: Measures Of Central

    135

    7. The mean of the data set of 1000 items is 5. From each item 3 is subtracted and then each number is multiplied by 2. The new mean will be _____

    (a) 4 (b) 5 (c) 6 (d) 7

  • Quantitative aptitude & Business Statistics: Measures Of Central

    136

    7. The mean of the data set of 1000 items is 5. From each item 3 is subtracted and then each number is multiplied by 2. The new mean will be

    (a) 4 (b) 5 (c) 6 (d) 7

  • Quantitative aptitude & Business Statistics: Measures Of Central

    137

    8. If each item is reduced by 15, AM is ____

    (a) reduced by 15 (b) increased by 15 (c) reduced by 10 (d) none of these

  • Quantitative aptitude & Business Statistics: Measures Of Central

    138

    8. If each item is reduced by 15, AM is ____

    (a) reduced by 15 (b) increased by 15 (c) reduced by 10 (d) none of these

  • Quantitative aptitude & Business Statistics: Measures Of Central

    139

    9. In a series of values if one value is 0 ____

    (a) both GM and HM are zero (b) both GM and HM are intermediate (c) GM is intermediate and HM is zero (d) GM is zero and HM is intermediate

  • Quantitative aptitude & Business Statistics: Measures Of Central

    140

    9. In a series of values if one value is 0 ____

    (a) both GM and HM are zero (b) both GM and HM are intermediate (c) GM is intermediate and HM is zero (d) GM is zero and HM is intermediate

  • Quantitative aptitude & Business Statistics: Measures Of Central

    141

    10.Histogram is useful to determine graphically the value of

    (a) Mean (b) Mode (c) Median (d) all of above

  • Quantitative aptitude & Business Statistics: Measures Of Central

    142

    10.Histogram is useful to determine graphically the value of

    (a) Mean (b) Mode (c) Median (d) all of above

  • Quantitative aptitude & Business Statistics: Measures Of Central

    143

    11.The positional measure of central Tendency

    (a) Arithmetic Mean (b) Geometric Mean (c) Harmonic Mean (d) Median

  • Quantitative aptitude & Business Statistics: Measures Of Central

    144

    11.The positional measure of central Tendency

    (a) Arithmetic Mean (b) Geometric Mean (c) Harmonic Mean (d) Median

  • Quantitative aptitude & Business Statistics: Measures Of Central

    145

    12.The average has relevance for (a) Homogeneous population (b) Heterogeneous population (c) Both (d) none

  • Quantitative aptitude & Business Statistics: Measures Of Central

    146

    12.The average has relevance for (a) Homogeneous population (b) Heterogeneous population (c) Both (d) none

  • Quantitative aptitude & Business Statistics: Measures Of Central

    147

    13.The sum of individual observations is Zero When taken from

    (a) Mean (b) Mode (C) Median (d) All the above

  • Quantitative aptitude & Business Statistics: Measures Of Central

    148

    13.The sum of individual observations is Zero When taken from

    (a) Mean (b) Mode (C) Median (d) All the above

  • Quantitative aptitude & Business Statistics: Measures Of Central

    149

    14.The sum of absolute deviations from median is

    (a) Minimum (b) Zero (C) Maximum (d) A negative figure

  • Quantitative aptitude & Business Statistics: Measures Of Central

    150

    14.The sum of absolute deviations from median is

    (a) Minimum (b) Zero (C) Maximum (d) A negative figure

  • Quantitative aptitude & Business Statistics: Measures Of Central

    151

    15.The mean of first natural numbers (a)n/2 (b)n-1/2 (c)(n+1)/2 (d) none

  • Quantitative aptitude & Business Statistics: Measures Of Central

    152

    15.The mean of first natural numbers (a)n/2 (b)n-1/2 (c)(n+1)/2 (d) none

  • Quantitative aptitude & Business Statistics: Measures Of Central

    153

    16.The calculation of Speed and velocity

    (a) G.M (b) A.M (c) H.M (d) none is used

  • Quantitative aptitude & Business Statistics: Measures Of Central

    154

    16.The calculation of Speed and velocity

    (a)G.M (b)A.M (c)H.M (d)none is used

  • Quantitative aptitude & Business Statistics: Measures Of Central

    155

    17. The class having maximum frequency is called

    A) Modal class B) Median class C) Mean Class D) None of these

  • Quantitative aptitude & Business Statistics: Measures Of Central

    156

    17. The class having maximum frequency is called

    A) Modal class B) Median class C) Mean Class D) None of these

  • Quantitative aptitude & Business Statistics: Measures Of Central

    157

    18. The mode of the numbers 7, 7, 9, 7, 10, 15, 15, 15, 10 is

    A) 7 B) 10 C) 15 D) 7 and 15

  • Quantitative aptitude & Business Statistics: Measures Of Central

    158

    18. The mode of the numbers 7, 7, 9, 7, 10, 15, 15, 15, 10 is

    A) 7 B) 10 C) 15 D) 7 and 15

  • Quantitative aptitude & Business Statistics: Measures Of Central

    159

    19. Which of the following measures of central tendency is based on only 50% of the central values?

    A) Mean B) Mode C) Median D) Both (a) and (b)

  • Quantitative aptitude & Business Statistics: Measures Of Central

    160

    19. Which of the following measures of central tendency is based on only 50% of the central values?

    A) Mean B) Mode C) Median D) Both (a) and (b)

  • Quantitative aptitude & Business Statistics: Measures Of Central

    161

    20. What is the value of the first quartile for observations 15, 18, 10, 20, 23, 28, 12, 16?

    A) 17 B) 16 C) 15.75 D) 12

  • Quantitative aptitude & Business Statistics: Measures Of Central

    162

    20. What is the value of the first quartile for observations 15, 18, 10, 20, 23, 28, 12, 16?

    A) 17 B) 16 C) 15.75 D) 12

  • Quantitative aptitude & Business Statistics: Measures Of Central

    163

    21. The third decile for the numbers 15, 10, 20, 25, 18, 11, 9, 12 is

    A) 13 B) 10.70 C) 11 D) 11.50

  • Quantitative aptitude & Business Statistics: Measures Of Central

    164

    21. The third decile for the numbers 15, 10, 20, 25, 18, 11, 9, 12 is

    A) 13 B) 10.70 C) 11 D) 11.50

  • Quantitative aptitude & Business Statistics: Measures Of Central

    165

    22. In case of an even number of observations which of the following is median?

    A) Any of the two middle-most value.. B) The simple average of these two

    middle values C) The weighted average of these two

    middle values. D) Any of these

  • Quantitative aptitude & Business Statistics: Measures Of Central

    166

    22. In case of an even number of observations which of the following is median?

    A) Any of the two middle-most value.. B) The simple average of these two middle

    values C) The weighted average of these two middle

    values. D) Any of these

  • Quantitative aptitude & Business Statistics: Measures Of Central

    167

    23. A variable is known to be _______ if it can assume any value from a given interval.

    A) Discrete B) Continuous C) Attribute D) Characteristic

  • Quantitative aptitude & Business Statistics: Measures Of Central

    168

    23. A variable is known to be _______ if it can assume any value from a given interval.

    A) Discrete B) Continuous C) Attribute D) Characteristic

  • Quantitative aptitude & Business Statistics: Measures Of Central

    169

    24. Ogive is used to obtain. A) Mean B) Mode C) Quartiles D) All of these

  • Quantitative aptitude & Business Statistics: Measures Of Central

    170

    24. Ogive is used to obtain. A) Mean B) Mode C) Quartiles D) All of these

  • Quantitative aptitude & Business Statistics: Measures Of Central

    171

    25. The presence of extreme observations does not affect

    A) A.M. B) Median C) Mode D) Any of these

  • Quantitative aptitude & Business Statistics: Measures Of Central

    172

    25. The presence of extreme observations does not affect

    A) A.M. B) Median C) Mode D) Any of these

  • THE END

    Measures Of Central Tendency

    Measures Of Central TendencyStatistics in Plural Sense as Statistical data.According to Prof.Horace Secrist:Slide Number 4Def:Measures of Central TendencySlide Number 6Types of Measures central tendency:Features of a good averageSlide Number 9Arithmetic Mean (A.M)Slide Number 11Slide Number 12Slide Number 13Arithmetic Mean for Discrete Series Arithmetic Mean for Continuous SeriesCalculation of Arithmetic mean in case of Continuous SeriesSlide Number 17Slide Number 18SolutionCalculation Of Arithmetic Mean in case of Less than series Solution:Let us first convert Less than series into continuous series as follows Calculation Of Arithmetic Mean in case of more than seriesSolution:Let us first convert More than series into continuous series as followsCalculation of Arithmetic Mean in case of Inclusive series Slide Number 25Slide Number 26Calculation of Arithmetic Mean in case of continuous exclusive series when class intervals are unequalSlide Number 28Slide Number 29Slide Number 30Combined Arithmetic Mean (A.M)Solution Weighted Arithmetic MeanSlide Number 34Slide Number 35Mathematical Properties of Arithmetic MeanSlide Number 37Slide Number 38Slide Number 39Slide Number 40Merits Of Arithmetic MeanSlide Number 42Slide Number 43Slide Number 44Limitations of Arithmetic MeanSlide Number 46MedianSlide Number 48Potential Problem with MeansMedianMedian for raw data Slide Number 52Median for raw dataMedian for continuous seriesQuartilesSlide Number 56Slide Number 57Slide Number 58Slide Number 59OctilesSlide Number 61Slide Number 62DecilesSlide Number 64Slide Number 65PercentilesSlide Number 67Relation Ship Between Partition ValuesCalculation of Median in case of Continuous SeriesSlide Number 70Slide Number 71Slide Number 72Merits of Median Limitations of MedianSlide Number 75ModeModeSlide Number 78Slide Number 79Mode for Continuous SeriesCalculation of Mode :Continuous SeriesSlide Number 82Slide Number 83Slide Number 84Relationship between Mean, Median and ModeSlide Number 86ExampleSolutionExampleMerits of ModeLimitations of ModeSlide Number 92Geometric meanSlide Number 94Computation of G.M -Discrete SeriesMerits of Geometric MeanSlide Number 97Limitations of Geometric MeanSlide Number 99Calculation of G.M :Individual SeriesComputation of G.M :Individual SeriesSlide Number 102Slide Number 103Slide Number 104Slide Number 105Weighted Geometric Mean Harmonic Mean (H.M)Slide Number 108Merits of Harmonic MeanSlide Number 110Limitations of Harmonic MeanSlide Number 112Calculation of H.M :Individual SeriesComputation of H.M :Individual SeriesSlide Number 115Slide Number 116Weighted Harmonic MeanSlide Number 118Slide Number 119Slide Number 120Slide Number 121Slide Number 122Slide Number 123Slide Number 124Slide Number 125Slide Number 126Slide Number 127Slide Number 128Slide Number 129Slide Number 130Slide Number 131Slide Number 132Slide Number 133Slide Number 134Slide Number 135Slide Number 136Slide Number 137Slide Number 138Slide Number 139Slide Number 140Slide Number 141Slide Number 142Slide Number 143Slide Number 144Slide Number 145Slide Number 146Slide Number 147Slide Number 148Slide Number 149Slide Number 150Slide Number 151Slide Number 152Slide Number 153Slide Number 154Slide Number 155Slide Number 156Slide Number 157Slide Number 158Slide Number 159Slide Number 160Slide Number 161Slide Number 162Slide Number 163Slide Number 164Slide Number 165Slide Number 166Slide Number 167Slide Number 168Slide Number 169Slide Number 170Slide Number 171Slide Number 172THE END