Lesson 23

Solving Percentage Problems

Problem 1

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 ________

 

Solution

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Problem 2

A store is having a 20%-off sale on all merchandise. If Mai buys one item and saves $13, what was the original price of her purchase? Explain or show your reasoning.

Solution

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Problem 3

The original price of a scarf was $16. During a store-closing sale, a shopper saved $12 on the scarf. What percentage discount did she receive? Explain or show your reasoning.

Solution

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Problem 4

  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.

Solution

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Problem 5

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?

Solution

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Problem 6

An ant travels at a constant rate of 30 cm every 2 minutes.

  1. At what pace does the ant travel per centimeter?
  2. At what speed does the ant travel per minute?

Solution

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(From Unit 2, Lesson 18.)