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Math Grade 6-8 Answer Key

Math: How to Set Up a Percent Proportion Practice

Writing part-over-whole equals percent-over-100

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Math: How to Set Up a Percent Proportion Practice

Writing part-over-whole equals percent-over-100

Math - Grade 6-8

Instructions: Read each problem carefully. Set up a percent proportion using part/whole = percent/100. Solve when asked and show your work.
  1. 1

    In a class of 30 students, 12 students ride the bus. Set up a percent proportion to find what percent of the class rides the bus.

    The percent is unknown, so use p over 100.

    The proportion is 12/30 = p/100. The part is 12 students, the whole is 30 students, and p represents the percent.
  2. 2

    A shirt costs $40. It is on sale for 25% off. Set up a percent proportion to find the amount of the discount.

    The proportion is x/40 = 25/100. The unknown x represents the discount amount, and 40 is the original price.
  3. 3

    A student answered 18 questions correctly on a 20-question quiz. Set up and solve a percent proportion to find the score as a percent.

    Correct answers are the part, and total questions are the whole.

    The proportion is 18/20 = p/100. Solving gives p = 90, so the student's score is 90%.
  4. 4

    A basketball player made 60% of her 15 shots. Set up a percent proportion to find how many shots she made.

    The proportion is x/15 = 60/100. The unknown x represents the number of shots made.
  5. 5

    A fruit basket has 8 apples and 12 oranges. Set up a percent proportion to find what percent of the fruit are apples.

    First find the total number of fruits.

    There are 20 pieces of fruit in all, so the proportion is 8/20 = p/100. The part is 8 apples and the whole is 20 total fruits.
  6. 6

    A store has 50 backpacks. If 18% of the backpacks are blue, set up a percent proportion to find the number of blue backpacks.

    The proportion is x/50 = 18/100. The unknown x represents the number of blue backpacks.
  7. 7

    A survey shows that 14 out of 35 students prefer science as their favorite subject. Set up and solve a percent proportion to find the percent of students who prefer science.

    Use the number who prefer science as the part.

    The proportion is 14/35 = p/100. Solving gives p = 40, so 40% of the students prefer science.
  8. 8

    A recipe uses 3 cups of sugar in a total mixture of 12 cups. Set up a percent proportion to find what percent of the mixture is sugar.

    The proportion is 3/12 = p/100. The part is 3 cups of sugar, the whole is 12 cups, and p represents the percent.
  9. 9

    A video game player completed 45% of a game that has 80 levels. Set up and solve a percent proportion to find how many levels were completed.

    The whole is the total number of levels.

    The proportion is x/80 = 45/100. Solving gives x = 36, so the player completed 36 levels.
  10. 10

    A school library has 240 books on display. If 30 of them are graphic novels, set up a percent proportion to find what percent of the display is graphic novels.

    The proportion is 30/240 = p/100. The part is 30 graphic novels, the whole is 240 books, and p represents the percent.
  11. 11

    A plant grew 6 centimeters this month. This growth is 15% of its total height. Set up a percent proportion to find the plant's total height.

    The whole is unknown, so put x in the denominator of the fraction on the left.

    The proportion is 6/x = 15/100. The unknown x represents the plant's total height because 6 centimeters is 15% of the whole height.
  12. 12

    A movie theater sold 72 tickets. If 40% of the tickets were child tickets, set up and solve a percent proportion to find the number of child tickets sold.

    Use x for the part because the number of child tickets is unknown.

    The proportion is x/72 = 40/100. Solving gives x = 28.8, so the setup shows that 40% of 72 is 28.8 tickets. In a real ticket count, this situation would need whole-number data.
LivePhysics™.com Math - Grade 6-8 - Answer Key