The ratio of boys to girls in a school CCA is 3 : 4. After 10 more boys join the CCA, the ratio of boys to girls becomes 7 : 8. How many girls are in the CCA?
Show Worked Solution
Worked Solution
Step 1: Let boys = 3k and girls = 4k (original ratio 3:4).
Step 2: After 10 boys join, boys = 3k + 10. Girls unchanged at 4k.
Step 3: New ratio condition: (3k + 10) / 4k = 7 / 8.
Step 4: Cross-multiply: 8(3k + 10) = 7(4k) → 24k + 80 = 28k → 4k = 80 → k = 20.
Step 5: Number of girls = 4k = 4 × 20 = 80.
Correct answer: 80
Want more questions like this? Superholic Lab has 10,000+ MOE-aligned questions with full worked solutions.
Start Free Trial — 7 Days Free