3-7 P

ERCENT EQUAT

IONS

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US

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S T

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WARM UP

Solve each equation.

1) 3.2(m + 5) = 16 2)

QUICK REVIEW!!!

A percent is a ratio that compares a number to 100. You can write a percent with the percent symbol as a fraction or a decimal.

Ex: 40% = = .40

SYMBOLS REPRESENT WORDS

is of wha

t = x n

What is 40% of 8?

n = .40 x 8

WRITE AN EQUATION TO MODEL EACH QUESTION.

1)What is 25% of 12?

2)3 is 75% of what?

3)What percent of 44 is 11?

4)16% of what is 200?

SALES

Suppose you work at a computer store. You earn 5% commission on everything you sell. How much do you earn on a computer you sell for $1900.

SURVEYS

55%

6%

12%

12%

15%

What do you Think Is the Number One

Problem in the World Today?

Drug Abuse OtherTerrorism HungerNuclear War

In a survey, 1650 students said that drug abuse is the number one problem in the world today. How many students were surveyed?

THINK ABOUT IT…

Can percents be numbers greater than 100? If yes, give an example.

EXAMPLE

Suppose SHS requires 36 hours of community service. You spent 56 hours volunteering at a hospital. What percent of the requirement have you fulfilled?

SIMPLE INTEREST

Today banks use compound interest, which we will study in Chapter 8. Compound interest is based on simple interest. Its formula is I = prt. (I = interest, p = principal, r = rate per year, t = time in years)

Ex: I = ? if p = $340, r = 6%, t = 3 yr

FINANCE

Suppose you invested $900 for two years. You earned $67.50 in simple interest. What was the annual rate of interest?

HOMEWORK

Pg 142-143 # 2, 4, 5, 8 , 9 , 11, 12, 13, 20, 22, 23, 27, 36, 38