4 boys and 6 girls can complete the work in 8 days, while 3 boys and 7 girls can complete it in 10 days. In how many days will 10 girls complete it?
Show answer & explanation
Correct answer: D
Explanation
Given:
4 boys + 6 girls → 8 days
3 boys + 7 girls → 10 days
(4 boys + 6 girls) × 8 = (3 boys + 7 girls) × 10
32 boys + 48 girls = 30 boys + 70 girls
2 boys = 22 girls
1 boy = 11 girls
Total work = (3 boys + 7 girls) × 10
= {(3 × 11) + (7 × 1)} × 10
= (33 + 7) × 10
= 40 × 10
= 400
Work rate of 10 girls = 10
Time = 400 / 10 = 40 days
10 girls will complete the work in 40 days.