Lesson 7

One Hundred Percent

Let’s solve more problems about percent increase and percent decrease.  

Problem 1

A bakery used 25% more butter this month than last month. If the bakery used 240 kilograms of butter last month, how much did it use this month?

Problem 2

Last week, the price of oranges at the farmer's market was $1.75 per pound. This week, the price has decreased by 20%. What is the price of oranges this week?

Problem 3

Noah thinks the answers to these two questions will be the same. Do you agree with him? Explain your reasoning.

  • This year, a herd of bison had a 10% increase in population. If there were 550 bison in the herd last year, how many are in the herd this year?
  • This year, another herd of bison had a 10% decrease in population. If there are 550 bison in the herd this year, how many bison were there last year?

Problem 4

Elena walked 12 miles. Then she walked 0.25 that distance.  How far did she walk all together?  Select all that apply.


\(12+0.25 \boldcdot 12\)




\(12 \boldcdot 1.25\)


\(12 \boldcdot 0.25\)


\(12 + 0.25\)

(From Unit 4, Lesson 5.)

Problem 5

A circle’s circumference is 600 m. What is a good approximation of the circle’s area?


300 m2


3,000 m2


30,000 m2


300,000 m2

(From Unit 3, Lesson 8.)

Problem 6

The equation \(d = 3t\) represents the relationship between the distance (\(d\)) in inches that a snail is from a certain rock and the time (\(t\)) in minutes.

  1. What does the number 3 represent?
  2. How many minutes does it take the snail to get 9 inches from the rock?
  3. How far will the snail be from the rock after 9 minutes?
(From Unit 2, Lesson 6.)