• Purpose: To solve problems solving percents.

• Homework: p. 317 -319 1-21 odd and problems 1-15 odd.

Formula

• Whenever a price is changed you can find the percent of increase or decrease by the following:

• Percent of change = change in price

• 1000 original price

• To find the change in price, you calculate the difference between the original price and the new price.

Examples

• Alyce originally paid $6500 for a ca 3 years ago. The same car costs $7400 today. What is the change in price?

• Find the change in price by subtracting $6500 from $7400.

• $7400 – $6500 = $900

• The price increased $900

Example #2

• The Bakers’ real estate taxes went from $1560 to $1683. What was the percent of increase?

• Let x = the percent of increase.• % of Change = change in price• 100 original• x = 78 **Cross Products.• 100 1560• 1560x = 7800; x = 5; 5% increase

Example #3

• The number of registered voters in Fresno increased by 14% over last year. There are now 9633 registered voters. How many voters were there last year?

• Let x = the # of voters last year. 9633 – x will = the change in # of voters.

• 14 = 9633 – x ** Cross Products.• 100 x• 14x = 100(9633 – x)• 14x = 963300 – 100x 114x = 963300• x = 8450; There were 8450 voters last year.

Joe invested $2000 at 51/4% annual interest and $3000 at 8 ½% annual interest. What percent

interest is he earning on his investment?

• A + B = Total• .0525(2000) + .085(3000) = 5000x• 10000[.0525(2000) + .085(3000) = 5000x]10000• 525(2000) + 850(3000) = 50,000,000x• 1,050,000 + 2,550,000 = 50,000,000x• 3,605,000 = 50,000,000x ; x = .072 ; 7.2%

Amt. Invested Rate Interest

Invest A 2000 .0525 .0525(2000)

Invest B 3000 .085 .085(3000)

Total 5000 x 5000x