Question

Thirty men take 20 days to complete a job working 9 hours a day.how many hour a day should 40 men work to complete the job?

Answer 1

total working hours required to complete the work = 30×20×9 =5400 hr
let, z hours/day required for 40 men to complete the work in 20 days,
then,
z×40×20 = 5400
=> z = 5400/800 = 27/4 =6.75hr
hence,
the required working time per day = 6.75hr/day
= 6 hr 45 min a day

I hope this helps.