A work can be finished by 10 men in 8 days and by 10 women in 7 days. In how many days will the work be finished if 10 women and 10 men work on alternate days, with the women starting on the first day?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 7
Given that
10 men working in 8 days is equal to 10 women working in 7 days
so, the efficiency of a man is 7
the efficiency of a woman is 8
Total work = 7 × 8 × 10 = 560
if 10 women and 10 men work on alternate days,
⇒ In 2 days, 8 × 10 + 7 × 10 = 80 + 70 = 150 work will be completed
⇒ In 6 days, 150 × 3 = 450 work will be completed
⇒ In 7 days, 450 + 80 = 530 work will be completed
The remaining work (560 - 530 = 30) is completed in 30/70, i.e. 3/7
Hence, the work will be finished in 7