1. APPLICATIONS Involving percents Percent 63% of homes have a computer 5% sales tax 15% commission Interpretation 63 out of 100 homes have a computer 5 cents in tax is charged for every 100 cents in merchandise. $15 is earned in commission for every $100 sold.

2. Percents come in a variety of application in day-to-day life. Many such applications follow the basic percent equation: amount = (percent)(base)

3. Example What percent of 60 is 25.2Step 1: Read the problem Step 2: Label the variables. Let x represent the unknown percent. Step 3: Create a verbal model. What percent of 60 is 25.2 x ∙ 60 = 25.2 Step 4: Write a mathematical equation. x ∙ 60 = 25.2 Step 5: Solve the equation 60x = 25.2 60 60 Step 6: Interpret the results and write the answer in words. x = 0.42, or 42%

4. Example A new digital camera cost $429.95 Compute the sales tax if the tax rate is 4% Step 1: Read the problem Step 2: Label the variables. Let x represent the amount of tax. sales tax = (tax rate)(price of merchandise) Step 3: Create a verbal model. Step 4: Write a mathematical equation. x = $17.198 x = $17.20 Step 5: Solve the equation Step 6: Interpret the results and write the answer in words. Sales tax is $17.20 The total cost = cost of merchandise + amount of tax $429.95 + $17.20 = $447.15 x = (0.04)($429.95)

5. Example A video game is purchased for a total of $48.15, including sales tax. If the tax rate is 7%, find the original price of the video game before the sales tax. Step 1: Read the problem Step 2: Label the variables. Let x represent the price of the videogame. (Original) + (Sales) = (total) price tax cost Step 3: Create a verbal model. Step 4: Write a mathematical equation. 1.07x = 48.15 1.07 1.07 x = 45 Step 5: Solve the equation Step 6: Interpret the results and write the answer in words. The original price is $45.00 x + 0.07x = $48.15 1.07x = 48.15

6. APPLICATIONS INVOLVING SIMPLE INTEREST ( SIMPLE ) = (PRINCIPAL)( ANNUAL )( TIME ) INTEREST INVESTED INTEREST RATE IN YEARS To find the simple interest earned on $2000 invested at 7.5% interest for 3 years, we have I = Prt Interest = ($2000)(0.075)(3) = $450