Ratios & Proportions
Simplifying ratios and solving proportions by cross-multiplying.
Score: 0 / 10
1. Simplify the ratio 8:12.
2. If 3 pens cost $6, how much do 5 pens cost?
3. Solve for x: 2/5 = x/20
4. Simplify the ratio 15:25.
5. A map scale is 1 cm : 50 km. How many km does 4 cm represent?
6. Solve for x: 6/9 = 8/x
7. The ratio of boys to girls in a class of 28 is 3:4. How many boys are there?
8. Simplify the ratio 18:24.
9. Solve for x: 4/x = 12/9
10. A recipe needs 2 cups of flour for every 3 cups of sugar. How much flour is needed for 9 cups of sugar?
Answer key — Ratios & Proportions
- B — 2:3. Divide both sides by 4: 8:12 = 2:3.
- B — $10. Each pen costs $6 ÷ 3 = $2, so 5 pens cost 5 × $2 = $10.
- B — 8. Cross-multiply: 2 × 20 = 5 × x, so 40 = 5x, and x = 8.
- A — 3:5. Divide both sides by 5: 15:25 = 3:5.
- B — 200 km. 4 × 50 km = 200 km.
- B — 12. Cross-multiply: 6 × x = 9 × 8, so 6x = 72, and x = 12.
- A — 12. 3 + 4 = 7 parts, so each part is 28 ÷ 7 = 4. Boys = 3 × 4 = 12.
- B — 3:4. Divide both sides by 6: 18:24 = 3:4.
- A — 3. Cross-multiply: 4 × 9 = 12 × x, so 36 = 12x, and x = 3.
- B — 6. The ratio 2:3 scales to x:9, so x = 2 × 3 = 6.
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