3-7 Percent equations

```WARM UP
Solve each equation.
1) 3.2(m + 5) = 16
s𝑠 s𝑠
2) − ==88
55 33
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
40
=
100
100
.40
SYMBOLS REPRESENT WORDS
is
of
what
=
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
What do you Think Is the
Number One Problem in
the World Today?
Drug Abuse
Terrorism
Nuclear War
Other
Hunger
15%
12%
55%
12%
6%
In a survey, 1650 students said that
drug abuse is the number one problem
in the world today. How many students
were surveyed?
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
```