Math 10: Basic Mathematics 1 Key Topics for Chapter 6  The 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 6  Problems 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 proportion 0% 100% 0 W% W = W%x28/28 = 21/28 W% =.75 W = 75 Wx28 = 100x21 Wx28/28 = 2100/28 W = 75

Math 10: Basic Mathematics 3 Key Topics for Chapter 6  Real 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 = P  r  t Compound: A = P  (1 + r/n) n  t