10 men can complete a piece of work in 15 days. They started work and after five days 10 women joined them and the work has finished in next 5 days. In how many days can 25 women finish the same piece of work?
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4 days
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5 days
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6 days
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8 days
C
Correct answer
Explanation
10 men's work in 15 days means 1 man-day = 1/150 of work. First 5 days: 10 men complete 50/150 = 1/3 work. Remaining 2/3 work finished by 10 men + 10 women in 5 days. So (10 men + 10 women) complete 2/3 work in 5 days, meaning they complete 2/15 per day. Since 10 men complete 1/15 per day, 10 women complete 1/15 per day, so 25 women complete 2.5/15 = 1/6 per day. Time needed = 1 / (1/6) = 6 days.