Question

15 men working 8 hours a day can build a wall in 20 days in how many days will 20 men build the same wall working 5 hours a day?

Answer 1

Method - 1:

(i)

Given that 15 men working 8 hours a day.

= > 15 * 8 = 120 man-hours per day.

The entire wall can be built in 20 days.

= > 120 * 20 = 2400 man-hours.

(ii)

Given that 20 men can build the same wall in 5 hours.

= > 20 * 5 = 100 man-hours per day.

Now,

To complete the work which requires 2400-man hours = 2400/100

= 24 days.

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Method - 2:

We know that Amount of work = Men * Days * Hours.

= > M1 * D1 * H1 = M2 * D2 * H2

= > 15 * 20 * 8 = 20 * D2 * 5

= > 2400 = 100D2

= > D2 = 2400/100

= > D2 = 24.

Therefore, 20 men can build the same wall working 5 hours a day in 24 days.

Hope this helps!