October 2, 2012Percent using proportions

Warm-up:1. At the peak of his performance, Mickey Mantle hit 1 homerun in every 9 at-bats. If Mantle had 468 at-bats in one season, how many home-runs did he hit?

HW 3.7: PG. 162 #15-21odds, 27-31odds, 37, 43

How do you find a percent of a number using proportions?

part

total%

100

For example, our last test was out of 57 points total. What would be your percentage if you received 52 points?

Ms. PD is shopping for her dad’s birthday gift (It’s on Oct. 8th!). She has a $50 gift certificate . Is it enough if she buys a $43 shirt with a 7% tax?

After Ms. PD bought a gift for her dad, she decided to shop for herself. She couldn’t decide which was the

better deal. An $80 dress that was 30% off or $60 boots that were 15% off. Which one will cost less?

Lesson 3.7 Percent of Change

When an increase or decrease is expressed as a percent, the percent is called the percent of change.

• If the number is greater than the original, it is a _________________________

• If the number is less than the original, it is a___________________________

Ms. PD was shopping again and missed a really good sale! =( She could have bought a nice blender for $50 and now it’s $70! Is the percent of change an increase or decrease, by what percent?

Original: 50New: 70

change

original%

100

Ms. PD’s dad didn’t like the shirt she bought him and returned it to buy another shirt that was originally $50, but is now $40. Is the percent of change an increase or decrease, by what percent?

Ms. PD was really upset because she caught her dad at the store the same day she shopped for the blender!