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.
Answer & explanation
Correct answer: option 2
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