40 men can complete a work in 30 days. They start work together and after every 10 days five men left the work. In how much time work will be complete.

36

40 men can do the work in 30 days

let efficiency of 1 men = 1

Total work = Efficiency × Number of days

Total work = 40 × 30 = 1200
Now

According to the question, after every 10th day, 5 men leave. That means

when the work began there were 40 men. After 10 days of work, there were 35

men, after another 10 days there were 30 men and so on.

40 men work in 10 days = 400 men days

35 men work in 10 days = 350 men days

30 men work in 10 days = 300 men days

Total work till now = 1050

remaining work = 1200 - 1050 = 150  & now men left are 25 men

so time taken = \(\frac{150}{25}\) = 6 days

Total days taken to finish the work = 30 + 6 = 36 days