Warmups

1. A tree casts a shadow 8 feet long. At the same time, a flagpole 10 feet tall casts a shadow 15 feet long. How tall is the tree?

2. Find I, if p = $950, r = 9%, t = 6 months

3. Find r, if I = $912, p = $7600, t = 4 years

4-5 Percent of Change

Objective: To solve problems involving percent of increase or

decrease.

Percent of Change Percent Increase: new amount/price goes up Percent Decrease: new amount/price goes down

Example 1: Mac reduced the price of the nano ipod from $179 to $139. What is the percent decrease?

Amount of decrease = _x_

Original # 100

(Big # - small #)

Another method You can also divide the fraction in your

calculator and then change the decimal to a percent: (do example 1 with this method)

Example 2

Ms. Lundblad’s groovy math club on campus had 56 members last year. This year there are 137 members. What is the percent increase?

Try with a PartnerIncrease or decrease? Round to nearest whole percent

3. original: $62 4. original: 322 people

new: $98 new: 289 people

TOO

5. original: $212

new: $230

6. Find t, if I = $1400, r = 7%, p = $625

Answers: 8% increase 32 years

Homework

Pg. 225 #12-20 All

Math Lab Warmups

1. A tree casts a shadow 6 feet long. At the same time, a flagpole 9 feet tall casts a shadow 21 feet long. How tall is the tree?

2. Find I, if p = $650, r = 3%, t = 9 months

3. Find r, if I = $250, p = $5400, t = 4 years

ZONK TIME!!