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Tham khảo tài liệu 'sat - mc grawhill part 31', ngoại ngữ, ngữ pháp tiếng anh phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 290 MCGRAW-HILL S SAT Answer Key 5 Percents Concept Review 5 1. x y or any unknown x is 100 T final amount - starting amount 2. -------- -------- -------x 100 starting amount 3. 1.30 4. 0.81 5. 2.20 6. -20 7. 5 x 26 x 19.23 8. .35x 28 x 80 9. 60 .15x x 400 10. 175 . Rephrase What percent of 20 is 35 or remember is over of equals the percent x 35 x -x- x 20 35 or 100 20 100 3 500 20x x 175 11. 25 . Use the percent change formula 1 500 -1 200 x 100 -300- x 100 25 1 200 1 200 12. -15 .168 80 x 100 -12 x 100 -15 80 80 13. 40 . 44 800 -32 000 x 100 x 100 40 32 000 32 000 14. 26. To increase a number by 30 multiply by 1.30 20 x 1.30 26. 15. 0.96. x 1.20 .80 0.96x 16. Because the two percentages are of different numbers. 17. 9.75 . Assume the original square has sides of length x and area x2. The new square then has sides of .95x and area of .9025x2. .9025x2 - x2 x 100 - 975xi x 100 -9.75 x2 x2 18. 50 of 28 which equals 14 19. 25 of 48 which equals 12 SAT Practice 5 1. D Miscellaneous expenses 3 500 - 2 200 - 600 700. As a percent of the total 700 3 500 20 . The total number of degrees in a pie graph is 360 so the sector angle 20 of 360 .20 x 360 72 . 2. 32 Assume the starting price is x. The final price is x 1.20 1.25 .80 1.10 1.32x which represents a 32 increase. Notice that you can t just add up the percent changes as we saw in Question 16 of the Concept Review. 3. C The total number of points is 40 80 120. The number of points she earned is .60 40 .90 80 24 72 96. 96 120 .80 80 . 4. D If you chose A remember 2 3 is NOT the same thing as 2 3 Don t forget that means 100. x 2 3 of 90 2 3 100 x 90 0.6 1 - 0.6 0.4 5. C If you chose B remember that the tax is 5 of the starting amount not the final amount. The final price must be 5 higher than the starting price. If the starting price is x then 8.40 1.05x. Dividing by 1.05 x 8.00. 6. B Let a population of Town A b population of Town B and c population of Town C. Since b is 50 greater than a b 1.50a. Since c is 20 greater .