Multiple choice

In one day, a man can do twice the amount of work done by a child in a day. It takes 40 days for 50 children, working 8 hours a day, to complete a piece of work. If 40 men work for 5 hours a day, then how many days will it take for them to complete the same piece of work?

  1. 40 days

  2. 60 days

  3. 80 days

  4. 10 days

  5. 120 days
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A Correct answer
Explanation

A man does twice the work of a child. 50 children working 8 hours for 40 days = 16000 child-units. 40 men (equivalent to 80 children) working 5 hours a day for D days: 80 * 5 * D = 400D. Setting 400D = 16000 gives D = 40.

AI explanation

Using the combined work formula of (M1 * D1 * H1) / W1 = (M2 * D2 * H2) / W2, substitute the given values. Since one man does twice the work of a child, 40 men equal 80 children. The equation is (50 * 40 * 8) / 1 = (80 * D * 5) / 1, which simplifies to 16000 = 400D. Solving for D gives 40 days.

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