Lesson 15Finding This Percent of That
Learning Goal
Let’s solve percentage problems like a pro.
Learning Targets
I can solve different problems like “What is 40% of 60?” by dividing and multiplying.
Lesson Terms
- percentage
Warm Up: Number Talk: Decimals
Problem 1
Find the value of each expression mentally.
Activity 1: Audience Size
Problem 1
A school held several evening activities last month—a music concert, a basketball game, a drama play, and literacy night. The music concert was attended by 250 people. How many people came to each of the other activities?
Attendance at a basketball game was 30% of attendance at the concert.
Attendance at the drama play was 140% of attendance at the concert.
Attendance at literacy night was 44% of attendance at the concert.
Are you ready for more?
Problem 1
50% of the people who attended the drama play also attended the music concert. What percentage of the people who attended the music concert also attended the drama play?
Activity 2: Everything Is On Sale
Problem 1
During a sale, every item in a store is 80% of its regular price.
If the regular price of a T-shirt is $10, what is its sale price?
The regular prices of five items are shown here. Find the sale price of each item.
item 1
item 2
item 3
item 4
item 5
regular price
sale price
You found 80% of many values. Was there a process you repeated over and over to find the sale prices? If so, describe it.
Select all the expressions that could be used to find 80% of
. Be prepared to explain your reasoning.
Lesson Summary
To find 49% of a number, we can multiply the number by
To find 135% of a number, we can multiply the number by
To find 6% of a number, we can multiply the number by
In general, to find