Lesson 7-5 for exercise sets. &KDSWHU
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Use the percent formula to find each percent.
1.What percent of 200 is 11? 2.0.3 is what percent of 0.5? 3.125 is what percent of 25?
4.For an important test, Juan studied for 2 h 20 min, while Ken studied for
two thirds of an hour. What percent of Ken’s study time was Juan’s?
Use a proportion to find each percent.
5.What percent of 2.5 is 2? 6.4.6 is what percent of 25? 7. What percent is of 10?
8.Ralph made 12 of his 25 free-throw attempts, while Maria made 20 of 50 attempts.
Who made the higher percent of free throws? How much higher?
9.Discuss and Write Show how you could use the fraction to solve
the opening problem about questionnaires. Tell which approach you
prefer, and explain why you prefer it.
350
500
1
5
What percent of 20 is 0.5? Use the formula.
r• bp
r• 200.5 Substitute 20 for band 0.5 for p.
r Simplify.
r 0.0252.5%
So 0.5 is 2.5% of 20.
Divide both sides by 20
to isolate r.
0.5
20
0.5
20
Divide. Rename the
decimal as a percent.
r• 20
20
1 30 is what percent of 8? Use a proportion.
Let nthe unknown percent.
Write the proportion.
30 • 100 8 n Cross multiply.
375 n
So 30 is 375% of 8.
Divide both sides
by 8 to isolate n.
8 n
8
3000
8
n
100
30
8
2
A circle graph shows how Earl’s cat spends
a 24-hour day. A 45° angle forms the section
of the circle representing the time the cat
spends eating. What percent of a day does
the cat spend eating? Use a proportion.
Let nthe unknown percent.
Write a proportion.
45 • 100 360 n Cross multiply.
12.5 n
Earl’s cat spends 12.5% of a day eating.
Divide both sides
by 360 to isolate n.
360 n
360
4500
360
n
100
45
360
3 What percent of 10 is?
Use the formula.
r • bp
r• 10 Substitute for pand 10 for b.
r •
r 5%
So is 5% of 10.^12
Rename the
fraction as a
percent.
5
100
1
20
Multiply by the
reciprocal of 10.
1
10
1
2
r• 10
10 Divide both sidesby 10 to isolate r.
1
2
1
2
10
1
2
1
(^42)