Lesson 12

Finding the Percentage

Let’s find unknown percentages.

Problem 1

A music store marks up the instruments it sells by 30%.

  1. If the store bought a guitar for $45, what will be its store price?
  2. If the price tag on a trumpet says $104, how much did the store pay for it?
  3. If the store paid $75 for a clarinet and sold it for $100, did the store mark up the price by 30%?

Problem 2

A family eats at a restaurant. The bill is $42. The family leaves a tip and spends $49.77.

  1. How much was the tip in dollars?
  2. How much was the tip as a percentage of the bill?

Problem 3

The price of gold is often reported per ounce. At the end of 2005, this price was $513. At the end of 2015, it was $1060. By what percentage did the price per ounce of gold increase?

Problem 4

A phone keeps track of the number of steps taken and the distance traveled. Based on the information in the table, is there a proportional relationship between the two quantities? Explain your reasoning.

number of steps distance in kilometers
950 1
2,852 3
4,845 5.1


(From Unit 2, Lesson 7.)

Problem 5

Noah picked 3 kg of cherries. Mai picked half as many cherries as Noah. How many total kg of cherries did Mai and Noah pick?


\(3 + \frac12\)


\(3 - \frac12\)


\(\left(1+\frac12\right)\boldcdot 3\)


\(1+\frac12\boldcdot 3\)

(From Unit 4, Lesson 4.)