Math 10: Basic Mathematics 1

Key Topics for Chapter 6The percentage, P%, represents the ratio

"P to 100"

And so, P% = P/100 = P x .01

E.g., 17% = 17/100 = .17

Decimals can be converted to a percentage by moving the decimal point 2 places to the right

E.g., .275 = 27.5%

Fractions can be converted to a percentage by first converting to a decimal

E.g., 2/5 = .4 = 40%

Math 10: Basic Mathematics 2

Key Topics for Chapter 6Problems involving percentages…

Many can be reduced to a question such as "What percent of 28 is 21?"

1.'Translate' directly to an equation

W% x 28 = 21

2.Solve using a proportion0%

100%

0

W%

28

21W 21100 28

=

W%x28/28 = 21/28W% = .75W = 75

Wx28 = 100x21Wx28/28 = 2100/28W = 75

Math 10: Basic Mathematics 3

Key Topics for Chapter 6Real world problems involving

percentages

"A car generally depreciates 25% its first year. A car is worth $27,300 after the first year. What was its original cost?"

Problems involving:

Percent increase and decrease

Taxes and commissions

Simple and compound interest

Simple: I = Prt

Compound: A = P(1 + r/n)nt