Name ———————————————————————
SECTION
3
Date ————————————
CA Standards
G6 NS 1.4
Ratio, Proportion, and Percent
Lesson 13: Finding the Number When
Percent Is Given
You can use a proportion to find the number when the percent is given.
Write the first ratio as the percent over 100. Write the second ratio as the
given number over n. Then solve the proportion for n using cross products.
EXAMPLE
80% of what number is 40?
part
part
whole
whole
80
40
}5}
n
100
}5}
80 3 n 5 100 3 40
80n 5 4000
80n
80
4000
80
}5}
n 5 50
Write a proportion.
Use given numbers and n.
Write cross products.
HINT
See Lesson 14
for another way
to solve problems
like this.
Multiply.
Divide each side by 80.
Simplify.
Copyright © by McDougal Littell, a division of Houghton Mifflin Company.
Practice: First Try
Use a proportion to answer each question.
1. 10% of what number is 7?
2. 30% of what number is 15?
3. 25% of what number is 8?
4. 100% of what number is 86?
5. 5% of what number is 1?
6. 10% of what number is 3?
7. 50% of what number is 13?
8. 80% of what number is 16?
9. 2% of what number is 1?
10. 75% of what number is 24?
11. 15% of what number is 9?
12. 20% of what number is 31?
13. 36% of what number is 72?
14. 2% of what number is 4?
15. 11% of what number is 66?
16. 30% of what number is 81?
Remediation Book Lesson 3.13
3. RATIO, PROPORTION
13. Finding the Number
Answer: 80% of 50 is 40.
91
Name ———————————————————————
Date ————————————
Practice: Second Try
Use a proportion to answer each question.
1. 15% of what number is 90?
2. 90% of what number is 45?
3. 2% of what number is 8?
4. 60% of what number is 12?
5. 75% of what number is 3?
6. 40% of what number is 32?
7. 9% of what number is 9?
8. 1% of what number is 20?
9. 30% of what number is 15?
10. 50% of what number is 50?
11. 5% of what number is 25?
12. 4% of what number is 2?
13. 1% of what number is 15?
14. 80% of what number is 20?
Extend Your Skills
15. Your friend saved $6 buying shoes on sale at 30% off the regular price.
16. A soccer team has 60% girls and 40% boys. If there are 9 girls on the team,
how many boys are on the team?
17. The Gazette charges $13.50 for 3 weeks of home newspaper delivery.
At this rate, what is the cost of 9 weeks of home delivery?
Puzzle
Complete the dot-to-dot to create a picture. But instead of connecting 1 to 2 to 3 to 4, etc.,
connect each of the answers you find to the questions in the order that they are given.
The picture will check out if you get it right!
80% of what number is 48?
50% of what number is 45?
30% of what number is 21?
25% of what number is 17?
40% of what number is 22?
75% of what number is 60?
90% of what number is 54?
92
Remediation Book Lesson 3.13
90
65
70
72
50
80
55
60
85
68
54
Copyright © by McDougal Littell, a division of Houghton Mifflin Company.
3. RATIO, PROPORTION
13. Finding the Number
What was the regular price of the shoes?