Lesson 15

Finding This Percent of That

Let’s solve percentage problems like a pro.

Problem 1

1. To find 40% of 75, Priya calculates $$\frac{2}{5} \boldcdot 75$$. Does her calculation give the correct value for 40% of 75? Explain or show how you know.
2. If $$x$$ represents a number, does $$\frac{2}{5} \boldcdot x$$ always represent 40% of that number? Explain your reasoning.

Problem 2

Han spent 75 minutes practicing the piano over the weekend. For each question, explain or show your reasoning.

1. Priya practiced the violin for 152% as much time as Han practiced the piano. How long did she practice?
2. Tyler practiced the clarinet for 64% as much time as Han practiced the piano. How long did he practice?

Problem 3

Last Sunday 1,575 people visited the amusement park. 56% of the visitors were adults, 16% were teenagers, and 28% were children ages 12 and under. Find the number of adults, teenagers, and children that visited the park.

Problem 4

Order from greatest to least:

• 55% of 180
• 300% of 26
• 12% of 700

Problem 5

Complete each statement.

• 20% of 60 is ________
• 25% of ________ is 6
• ________% of 100 is 14
• 50% of 90 is ________
• 10% of ________ is 7
• 30% of 70 is ________

(From Unit 3, Lesson 14.)

Problem 6

A shopper needs 24 sandwich rolls. The store sells identical rolls in 2 differently sized packages. They sell a six-pack for $5.28 and a four-pack for$3.40. Should the shopper buy 4 six-packs or 6 four-packs? Explain your reasoning.

(From Unit 3, Lesson 9.)

Problem 7

On a field trip, there are 3 chaperones for every 20 students. There are 92 people on the trip. Answer these questions. If you get stuck, consider using a tape diagram.

1. How many chaperones are there?
2. How many children are there?
(From Unit 2, Lesson 15.)