Pre-Algebra Quiz: Solving Proportions
7 questions · exam conditions
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Solving ProportionsQuestion 1 of 7

On a map, 1.5 inches represents 60 miles. Two cities are 8.25 inches apart on the map. A car travels between these cities at an average speed of 55 mph. How long will the trip take?

5 hours
6 hours
6.5 hours
7 hours
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Pre-Algebra Quiz

Pre-Algebra Quiz: Solving Proportions

Practice Solving Proportions in Pre-Algebra with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Solving Proportions, giving you a quick way to practice the rules, question types, and explanations that matter most for Pre-Algebra.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

On a map, 1.5 inches represents 60 miles. Two cities are 8.25 inches apart on the map. A car travels between these cities at an average speed of 55 mph. How long will the trip take?

  1. 5 hours
  2. 6 hours (correct answer)
  3. 6.5 hours
  4. 7 hours
Explanation: First find the actual distance: 1.5 inches60 miles=8.25 inchesx miles\frac{1.5 \text{ inches}}{60 \text{ miles}} = \frac{8.25 \text{ inches}}{x \text{ miles}}. Cross multiply: 1.5x=60×8.25=4951.5x = 60 \times 8.25 = 495, so x=4951.5=330x = \frac{495}{1.5} = 330 miles. Time = 330 miles55 mph=6\frac{330 \text{ miles}}{55 \text{ mph}} = 6 hours. Choice A uses incorrect distance calculation. Choice C results from using 50 mph instead of 55 mph. Choice D comes from arithmetic errors in the proportion setup.

Question 2

A recipe calls for 3 cups of flour to make 18 cookies. Maria wants to make 42 cookies but only has 6.5 cups of flour available. How many additional cups of flour does she need?

  1. 0.5 cups (correct answer)
  2. 1.0 cups
  3. 1.5 cups
  4. 2.0 cups
Explanation: First, set up a proportion: 3 cups18 cookies=x cups42 cookies\frac{3 \text{ cups}}{18 \text{ cookies}} = \frac{x \text{ cups}}{42 \text{ cookies}}. Cross multiply: 3×42=18x3 \times 42 = 18x, so 126=18x126 = 18x, which gives x=7x = 7 cups needed. Since Maria has 6.5 cups, she needs 7−6.5=0.57 - 6.5 = 0.5 additional cups. Choice B incorrectly calculates 7−6=17 - 6 = 1. Choice C uses the wrong proportion setup. Choice D doubles the error from choice B.

Question 3

A recipe for fruit punch calls for cranberry juice and apple juice in a ratio of 2:7. If Sarah uses 3.5 cups of apple juice, how much cranberry juice should she use to maintain the same ratio?

  1. 2.5 cups
  2. 1.5 cups
  3. 2 cups
  4. 1 cup (correct answer)
Explanation: When you see a ratio problem, you're looking at a relationship between two quantities that must stay constant. Here, cranberry juice and apple juice have a 2:7 ratio, meaning for every 2 parts cranberry juice, there are 7 parts apple juice. To solve this, set up a proportion. The original ratio is 2:7 (cranberry:apple), and you know Sarah uses 3.5 cups of apple juice. Let xx represent the unknown amount of cranberry juice: 27=x3.5\frac{2}{7} = \frac{x}{3.5} Cross multiply: 2×3.5=7×x2 \times 3.5 = 7 \times x, which gives you 7=7x7 = 7x. Solving for xx: x=1x = 1. So Sarah needs 1 cup of cranberry juice, making D correct. Let's examine why the other answers miss the mark. Choice A (2.5 cups) likely comes from incorrectly setting up the proportion as 72=3.5x\frac{7}{2} = \frac{3.5}{x}, flipping the ratio. Choice B (1.5 cups) might result from subtracting 2 from 3.5 instead of using proportional reasoning. Choice C (2 cups) could come from simply using the numerator of the original ratio without considering the proportional relationship. Study tip: Always write out your ratios clearly and double-check which quantity corresponds to which number. A quick verification helps too—does 1:3.5 simplify to 2:7? Yes, because 13.5=27\frac{1}{3.5} = \frac{2}{7} when you multiply both parts of 1:3.5 by 2.

Question 4

Two similar triangles have a ratio of corresponding sides of 2:5. If the perimeter of the smaller triangle is 24 cm, and the area of the larger triangle is 150 cm², what is the area of the smaller triangle?

  1. 24 cm² (correct answer)
  2. 60 cm²
  3. 96 cm²
  4. 37.5 cm²
Explanation: The ratio of corresponding sides is 2:5, so the ratio of areas is (2:5)2=4:25(2:5)^2 = 4:25. If the larger triangle has area 150 cm², then smaller area150=425\frac{\text{smaller area}}{150} = \frac{4}{25}. Cross multiply: 25×smaller area=4×150=60025 \times \text{smaller area} = 4 \times 150 = 600, so the smaller area is 60025=24\frac{600}{25} = 24 cm². Choice B incorrectly uses the linear ratio instead of the squared ratio. Choice C uses an incorrect proportion setup. Choice D incorrectly calculates 1504\frac{150}{4}.

Question 5

A machine can produce 450 widgets in 6 hours. Working at the same rate, how many widgets can 3 such machines produce in 8 hours?

  1. 900 widgets
  2. 1200 widgets
  3. 1800 widgets (correct answer)
  4. 2400 widgets
Explanation: First find the rate per machine: 450 widgets6 hours=75\frac{450 \text{ widgets}}{6 \text{ hours}} = 75 widgets per hour per machine. With 3 machines for 8 hours: 3×75×8=18003 \times 75 \times 8 = 1800 widgets. Choice A incorrectly uses only 2 machines or 6 hours instead of 8. Choice B uses 2 machines for 8 hours. Choice D incorrectly calculates 450×86×3450 \times \frac{8}{6} \times 3 with an arithmetic error.

Question 6

A car travels 240 miles in 4 hours. At this same rate, how long will it take to travel 420 miles?

  1. 6 hours
  2. 6.5 hours
  3. 7 hours (correct answer)
  4. 7.5 hours
Explanation: Set up the proportion: 240 miles4 hours=420 milesx hours\frac{240 \text{ miles}}{4 \text{ hours}} = \frac{420 \text{ miles}}{x \text{ hours}}. Cross multiply: 240x=420×4=1680240x = 420 \times 4 = 1680, so x=1680240=7x = \frac{1680}{240} = 7 hours. Choice A incorrectly uses 420240×4=7\frac{420}{240} \times 4 = 7 but makes an arithmetic error. Choice B results from incorrectly calculating 420240=1.75\frac{420}{240} = 1.75 then adding to 4. Choice D comes from adding the extra 180 miles divided by an incorrect rate.

Question 7

The ratio of boys to girls in a school is 3:5. If there are 96 more girls than boys, how many students are in the school?

  1. 256 students
  2. 320 students
  3. 480 students
  4. 384 students (correct answer)
Explanation: When you see ratio problems with a given difference between quantities, you need to use the ratio parts to find the actual numbers. The ratio 3:5 means for every 3 boys, there are 5 girls, so girls outnumber boys by 2 ratio parts (5 - 3 = 2). Since there are 96 more girls than boys, and this difference represents 2 ratio parts, each ratio part equals 96÷2=4896 \div 2 = 48 students. Now you can find the actual numbers: boys = 3×48=1443 \times 48 = 144 and girls = 5×48=2405 \times 48 = 240. The total is 144+240=384144 + 240 = 384 students, which is answer D. Let's examine why the other answers are wrong. Answer A (256) likely comes from incorrectly assuming the difference of 96 represents just one ratio part, leading to boys = 144 and girls = 112 (which actually gives boys more than girls). Answer B (320) might result from miscalculating the ratio parts or making an arithmetic error in the final addition. Answer C (480) could come from incorrectly thinking each ratio part equals 60 instead of 48, possibly from dividing 96 by something other than 2. The key strategy for ratio problems is to always identify what the given difference represents in terms of ratio parts. Here, the 96-student difference equals the difference between the ratio parts (5 - 3 = 2 parts). Once you find the value of one part, multiply by each ratio number to get the actual quantities.