Lesson 10

EstimationGrade 7Week #5

Founders’ Hall Math - PSSA

Round decimals and fractions and then compute with the rounded numbers to

estimate a solution.

$51,950 rounds to $52,000

Round to the greatest place. 18.9 rounds to 2011.05 rounds to 10

Round each fraction to the nearest whole number.4 rounds to 5 9 rounds to 9

78

15

Your friend says that 598.034 – 189.95 = 308.084. Is your friend’s answer correct?

598.034 rounded to its greatest place is 600

189.95 rounded to its greatest place is 200

So, a good estimate of 598.034 – 189.95 is:600 – 200 = 400

Your friend’s answer is incorrect because the estimated difference is 100 to your friend’s answer.

Check it out with the Coach

Sample Test Questions1. Chandra bought 3 T-shirts that cost $10.95 each, and 2 caps that cost $9.95 each. Which of the following is the best estimate of her total purchase?

A $50B $60C $70D $80

Answer A $50

2. Darlene earns $4,128 per month. She works 21 days per month. Which of the following is the best estimate of the amount she earns per day?

A $150B $200C $250D $300

Answer B $200

3. A rectangular lot measures 49.85 m long and 21.6 m wide. Which of the following is the best estimate of the area of the lot?

A 100 sq inB 800 sq inC 1,000 sq inD 8,000 sq in

Answer C 1,000 sq in

4. Use estimation to determine the most reasonable quotient for 46.28 / 2.6.

A 0.178B 1.78C 17.8D 178

Answer C 17.8

5. Maria painted 4 feet of wood trim on Thursday, 9 feet on Friday, and 15 feet on Saturday. Use estimation to determine which of the following is total number of feet of trim Maria painted.

A 18 feet

B 27 feet

C 29 feet

D 39 feet

Answer c 29 feet

781

5110

720

740

720

740

740

6. The population of Philadelphia in the year 1900 was 1,293,697. In the year 2000, the population was 1,517,550. Which of the following is the best estimate of the increase in the population from 1900 to 2000?

A 100,000B 200,000C 300,000D 400,000

Answer B 200,000

7. Jeannine is 67 inches tall. Her brother Nicholas is 59 inches tall. Which is the best estimate of how much taller Jeannine is?

A 13 inchesB 11 inchesC 9 inchesD 7 inches

Answer C 9 inches

111618

8. Without doing the multiplication, which must be the product for 105.6 x 0.22?

A 0.232232B 2.32232C 23.232D 232.32

Answer C 23.232

Without doing the multiplication, which must be the product for 2 x 7 ?

A 9

B 12

C 18

D 21

Answer C 18

13

56

518

518

518

518

518

10.Patricia will make car payments of $314.99 per month for 4 years. Which of the following is the best estimate of the total amount she will pay after 4 years?

A $12,000B $15,000C $18,000D $21,000

Answer B $15,000

11. A. 3 rounds to 4 3 rounds to 3

4 x 3 = 12

My friend’s answer of 19 is incorrect.

12 is the correct estimate.

11. B.

3429

154

29 9

435 36

112x == 12

Progress Check For Lessons 1-10

1. What is written as a percent?

A 18%B 27%C 45%D 81%

Answer C 45%

920

2. Which shows these numbers ordered from least to greatest?

4.012, 3 , 3.475, 3

A 3.475, 3 , 3 , 4.012

B 3.475, 3 , 3 , 4.012

C. 3 , 3.475, 3 , 4.012

D. 3 , 3 , 3.475, 4.012

Answer A

58

1215

58

1215

58

1215

58

1215

58

1215

3. Daisy records the temperature in her garden every morning at 6 A.M. Below are the temperatures from the last 3 days.

2 ˚ F, -4˚ F, -1˚ F

Which of the following lists the temperatures in order from least to greatest

A -1˚, 2˚, -4˚B 2˚ , -1˚, -4˚C -4˚, -1˚, 2˚D -1˚, -4˚, 2˚

Answer C -4˚, -1˚, 2˚

4. Which point on the number line is closest to ?

A B C D

-1 0 1 2

A point AB point BC point CD point D

Answer B point B

5. Jocee paid $92 to rent skis for 4 days. At this rate, how much does it cost to rent skis for one day?

A $20B $22C $23D $25

Answer C $23

6. Robin and Julie picked apples on a farm. The ratio of the number of apples that Robin picked to the number of apples that Julie picked was 11:8. Together, they picked 114 apples. How many apples did Julie pick?

A 48B 52C 60D 66

Answer A 48

7. Bridgette was making gift baskets for her friends. She put 7 pieces of candy in each basket. If she used 98 pieces of candy, how many gift baskets did Bridgette make?

A 11B 12C 13D 14

Answer D 14

8. What is the value of this expression?

96 – 3 (4² - 2³) x 4

A 0B 18C 192D 2,976

Answer A 0

9. There are 13 girls in Mrs. Jackson’s class of 22 students. Which ratio compares the number of boys to the number of students in the class?

A 13/22B 13/9C 9/13D 9/22

Answer D 9/22

10.A radio station plays 3 songs in 12 minutes. If the station continues to play songs at the same rate, how many songs will it play in one hour?

A 12B 15C 18D 21

Answer B 15

11.The restaurant bill for a group of friends came to $89.75. The friends want to leave a tip of 20%. Which of the following is the best estimate of how much they should leave as a tip?

A $9B $12C $18D $24

Answer C $18