sohailmbaprep wrote:If 6 men can do a piece of work in 30 days of 9 hours each, how many men will it take to do 10
times the amount of work if they work for 25 days of 8 hours?
The hourly rate of 6 men is 1/(30 x 9) = 1/270, and hence the hourly rate of 1 man is (1/270)/6 = 1/1620. The hourly rate to do 10 times the amount of work for 25 days of 8 hours is 10/(25 x 8) = 10/200 = 1/20. Since one man's hourly rate is 1/1620, we need (1/20)/(1/1620) = 1/20 x 1620 = 81 men.
Alternate Solution:
The job done by 6 men in 30 days at 9 hours per day takes 30 x 9 = 270 hours. 10 times the amount of work will take 6 men 270 x 10 = 2700 hours. To do this job in 25 x 8 = 200 hours, in other words, to decrease the time by a factor of 2700/200 = 13.5, we need to increase the number of men by a factor of 13.5. Thus, we need 6 x 13.5 = 81 men.
Answer: 81
