Working with Percents

Understanding Percents Per = “out of” Cent = “one hundred” Put them together and the word percent means “out of one hundred”

Percents & Proportions Since we know percents are out of 100 it is easy to set up a proportion to help us solve percent problems…

Example 1 75% of 40 is what number? x 40 75

Example 2 30% of 60 is what number? x 60 30

Example 3 14% of 88 is what number? x 88 14

Example 4 31 is what percent of 124? x

Example 5 6 is what percent of 400? x

Example is what percent of 105? x

Example 7 30 is 75% of what number? 30 x 75

Example is 65% of what number? 156 x 65

Example 9 12 is 1.5% of what number? 12 x 1.5

Percent Word Problems 1)Determine what information you already have What is the part? What is the whole? What is the percent? 2)Plug into the proportion 3)Cross multiply to solve 4)Label your answer

Example 1 Heather is downloading a song from iTunes. The song she is downloading will take 40 seconds to complete. So far it is 75% of the way to completion. How long has she been waiting so far? What is the part? What is the whole? What is the percent?

Example 2 Josephine recently took a test in her Science class. She earned 11 out of 16 possible points. What percent did she earn? What is the part? What is the whole? What is the percent?

Example 3 Mrs. Padmanabha likes to bake for the teacher’s on Team Galileo. Last week, the teachers ate 9 of the cupcakes Mrs. Padmanabha made. If that was 60% of the cupcakes, how many cupcakes did Mrs. Padmanabha make? What is the part? What is the whole? What is the percent?