Here, we need to apply the formula M1 D1 H1 E1 / W1 = M2 D2 H2 E2 / W2, where
M1 = 10 men
D1 = 24 days
H1 = 9 hours/day
W1 = W2 = Work to be done
E1 = E2 = Efficiency of each man
M2 = 15 men
D2 = Days required by 15 men
H2 = 6 hours/day
So, we have
10 x 24 x 9 = 15 x 6 x D2
=> D2 = 24
Therefore, 15 men working 6 hours / day would require 24 days to complete the work.
Note : Here, 10 men working 9 hours a day is equivalent to 90 working hours by 1 man. 15 men working 6 hours / day is also equivalent to 90 working hours by 1 man. Hence, the number of days required to complete the work would not change.
