How do you compute successive percents ?

1. How do you compute successive percents? For example: Eli bought a computer that was on sale for 30% off its original price of $500. Eli also used a coupon for a 15% discount on the sale price. The tax rate was 7.25%. How much did Eli pay for the computer?

2. In this lesson you will learn how to compute successive percentagesby using proportions and equations.

3. Using Equations Percent as Decimal x Amount 50% = 0.5 0.5 x 300= 150

4. Proportions Have Equal… Between Ratios 100 x 3 = 300 50 x 3 = 150 Within Ratios 50 x 2 = 100 150 x 2 = 300

5. Proportions Also Have Equal Cross Products 100v = 1,500 v = 150

6. Total Percent Change = Sum of Percent Changes 25% off sale, 10% off sale price coupon, 8% Tax -25% + -10% + 8% = -27% 25% off Original Price = Sale Price 10% off Sale Price = Coupon Price 8% more than Coupon Price = Final price

7. Add or Subtract?

8. Eli bought a computer that was on sale for 30% off its original price of $500. Eli also used a coupon for a 15% discount on the sale price. The tax rate was 7.25%. How much did Eli pay for the computer?

9. Using Between Ratios Using Within Ratios

10. Using Cross Products 100x = 1,500 x = $150

11. Using Equations 500 x 0.3 = $150

12. Original-(Original x %off) = Sale Price 500-(500x0.3) = 500-150 = $350 500 x (1—0.3) = 500 x 0.7 = $350 30% off is the same as 70% of original amount

13. 15% coupon off of $350 350 – (350 x 0.15) = 350 – 52.50 = $297.50 350 x (1—0.15) = 350 x 0.85 = $297.50

14. $297.50 plus 7.25% Tax 297.50+(297.50x0.0725)=297.50+21.57= $319.07 297.50 x (1 + 0.0725)= 297.50 x 1.0725 = $319.07 Adding 7.25% is the same as 107.25% of the original amount

15. -35% + -15% + 7.25% = -42.75% 500 – (500 x .4275) = 500 – 213.75 = 286.25 $286.25 versus $319.07 35% off Original Price = Sale Price 15% off Sale Price = Coupon Price 7.25% more than Coupon Price = Final price

16. In this lesson you have learned how to calculate successive percentages by using a proportions and equations.

17. After eating at your favorite restaurant, you know the bill before tax is $52.60 and the sales tax is 8%. You decide to leave a 20% tip for the waiter based on the pre-tax amount. How much should you leave for the waiter? How much will the bill be with tax? How much will you spend in total?

18. Tom has raised $2,000 and started a charity to provide book bags of school supplies for poor children. Tom packs each bag with 2 notebooks and 10 pencils. At the store the original price of 1 book bag is $22.50, of 1 notebooks is $3.25, and of 1 pencil is $0.19. However, all items are on sale for 30%. Tom also receives an additional 10% discount off of the sale price, because the products are for a charity. Tax is 8.25%. How many book bags can Tom make?

19. Pretend that you deposited $500 in 3 different savings accounts at three banks. Bank A provides customers with 2% interest on their investments per month. Bank B provides 5% and Bank C offers 7%. Create a table of how much money that you will have in each account at the end of each month. How do the amounts compare after 1 year? What about after 5 years?

20. Pretend that had a job that earned 5% commission of your sales. How much would you need to sell to earn one million dollars pre-tax? Your state government deducts 12% from your earnings. The federal government deducts 6.5% from your earnings. How much would you need to sell to earn one million dollars post-tax?

21. Joe’s bill at the restaurant was $52.70. He decided to leave his server 15% tip on the pre-tax bill. The tax rate is 8%. How much of a tip will he leave? How much is the bill after tax? How much will he spend in total? A $750 computer is on sale for 25% off. You also have a coupon for 10% off the sale price. Tax is 8%. How much will the computer cost?