Question

If it takes eight men ten hours to build a wall, how long would it take four men?​

Answer 1

The construction of the wall requires 10 hours * 8 men = 80 man-hours. So if 4 men are employed they will complete the wall in 80 man-hours/4 men = 20 hours. Mathematically, the answer is 20 hours.

Answer 2

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8 men ===> 10 hours

1 man ===> 8 × 10 hours {Unitary method}

Now,

Time taken by 4 men ===> Time taken by 1 man / 4

= (10×8) / 4

= 20 hours

Time taken by 4 men to build a wall is 20 hours

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