Ed took 5 tests and his average was 85. If his average after the first three tests was 83, what’s the average of the last two tests.

On Thursday, 20 out of 25 students took a test and their average was 80. On Friday, the other 5 students took it and their average was 90. What was the class average?

Finishing Mean/Median

Examples Average salaries of professional football

players.

Scores on a test when there’s one that hasn’t been made up yet.

Average salaries of 1st year teachers

mod

mean

median

e

mode median mean

modmean median e

Boxplots

Boxplots

Provides information about the center, spread, and symmetry (skewness) of the data.

Multiple boxplots can be used to compare data.

Constructing a boxplot.

Find the five number salary Minimum Q1

Median Q3

Maximum Plot on number line. Box in the IQR and draw whiskers to

the min & max.

5, 8, 13, 17, 22, 24, 25, 27, 29, 30

8, 10, 22, 24, 25, 25, 26, 27, 45, 72

Graph & Describe

Outlier

A value is considered an outlier if it is more than 1.5 IQR away from the closest end of the box.

5, 7, 9, 9, 10, 11, 13, 17, 29

Find if there are any outliers.

Using the Calculator.

Put data in List Press 2nd stat Turn plot 1 on and choose boxplot Zoom 9

22, 27, 33, 39, 57, 88, 110

Comparative

Measure your longest finger. Create boxplot of girls vs boys. Describe

Variation

Standard Deviation

This is a measure of the average distance of the observations from their mean.

Variance – it is the average of the squared distance from the mean.

Homework

Page 71 (89, 91, 93, 95, 97, 105, 107-110)

Bring Candy for tomorrow!