How many more days will be needed to finish the job?

Question

32 men can finish a job in 32 days, If after 8 days manpower is increased by 28, then how many more days will be needed to finish the job?

Answer 1

Answer is 12.8 days.

32 men finish job in 32 days.----------> 1 mean finish job in 32*32 days.
so one men complete per day 1/(32 x 32) of work.

so 32 men in 8 days complete (32 x 8)/(32 x 32) of work ------> 1/4 of work -----> remaining work is 3/4.
now men is increased by 28 so now total men is 60.
now per day compeleted work is ------> 60 x work one men complete per day ------> 60/32 x32= 15 / 256

days need to finish the job = remining work / now per day compeleted work = (3/4)/(15 / 256) = 12.8 days.