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PERCENTS ARE RATIOS Lesson 27 Section 2 Percent increase or decrease Example 1. A blouse that usually sells for $32 is on sale at 25% off. How much do you pay? Answer. "25% off" means that a quarter of the price will be subtracted. A quarter of 32 is 8. (Lesson 14.) Therefore you will pay $8 less. You will pay $32$8 = $24. Example 2. A VCR that usually sells for $240 is being sold at a
taken off. A third of 240 is 80. (Lesson 15, Question 2.) You will pay $240$80 = $160. Example 3. A CD that last week sold for $15 now costs 10% more. How much does it cost now? Answer. 10% of $15 is $1.50. (To take 10% -- a tenth -- separate one decimal place. Section 1, Example 7.) Therefore it now costs $15 + $1.50 = $16.50. Example 4. Calculator problem. An item costs $39.95, and the tax
Solution. On simple calculators, press
That is, press the + key. Do not press = . See
You will pay $43.45. Alternatively, the total cost is 100% of the item plus 8.75%, which is a total of 108.75%. Press
Example 5. Calculator problem Marlene's rent was $672.50. It was reduced by 6½%. What is her present rent? Solution. This time press − . Press
See
Her present rent is $628.79. Estimations When using a calculator, and in general, the student should have some idea where the answer lies. With a calculator it is very easy to press a wrong number. Example 6. How much is 26.2% of $44.59? Choose the best answer: $.11 $1.10 $11 $110 Answer. $11. Because 26.2% is close to 25%, which is a quarter. A quarter of 44 is 11. Example 7. How much is 49. 3% of $205.16? Choose the best answer: $1,020 $102 $10.20 $1.02 Answer. $102. $49. 3% is close to 50%, which half. Example 8. 98 is approximately what percent of 204? 16% 48% 52% 89% Answer. 48%. Because 98 is a little less than half of 204. Example 9. What percent of 40 is 11? 6% 24% 27% 9% Answer. 27%. Because 11 is a little more than a quarter (25%) of 40, which is 10. Please "turn" the page and do some Problems. or Continue on to the next Lesson. Introduction | Home | Table of Contents Please make a donation to keep TheMathPage online. Copyright © 2001-2007 Lawrence Spector Questions or comments? E-mail: themathpage@nyc.rr.com |