7th Grade Math

Multi-Part Lesson Review

Percents

Percent of a Number (Lesson 1B)

Find each number. Round to the nearest

tenth if necessary.

11. Find 78% of 50.


12. 45.5% of 75 is what number?


13. What is 225% of 60?


14. 0.75% of 80 is what number?

EXAMPLE 1 Find 24% of 200.

24% of 200

= 24% × 200 Write the expression.

= 0.24 × 200 Write 24% as a decimal.

= 48 Multiply.

So, 24% of 200 is 48.

Percent and Estimation (Lesson 1C)

Estimate.

15. 25% of 81 16. 33% of 122


16. 77% of 38 18. 19.5% of 96

Estimate by using 10%.

19. 12% of 77 20. 88% of 400

EXAMPLE 2 Estimate 52% of 495.

52% ≈ 50% or _^12 , and 495 ≈ 500.

52% of 495 ≈ _^12 · 500 or 250.

So, 52% of 495 is about 250.

Lesson 1

Proportions and Equations

The Percent Proportion (Lesson 2B)

Find each number. Round to the nearest

tenth if necessary.

21. 6 is what percent of 120?


22. Find 0.8% of 35.


23. What percent of 375 is 40?


24. SOCCER A soccer team lost 30% of
    their games. If they played 20 games,
    how many did they win?


25. PHONE SERVICE A family pays $21.99 each
    month for its long distance phone service.
    This is 80% of the original price of the
    phone service. What is the original price
    of the phone service? Round to the
    nearest cent if necessary.

EXAMPLE 3 What percent of 90 is 18?

_^18

90

= _n

100

Write the proportion.

18 · 100 = 90 · n Find the cross products.

1,800

_ 90 = _ 9090 n Divide each side by 90.

20 = n.

So, 18 is 20% of 90.

EXAMPLE 4 52 is 65% of what number?

_^52 w = _^65

100

Write the proportion.

52 · 100 = w · 65 Find the cross products.

5,200

_ 65 = _ 6565 w Divide each side by 65.

80 = w

So, 52 is 65% of 80.

Lesson 2

Chapter Study Guide and Review 367

366_370_C06_SGR_895130.indd 367 12/30/09 4:12 PM