Exams

A tyre has 3 punctures. The first puncture alone would have made the tyre flat in 9 minutes, the second alone would have done it in 18 minutes, the third alone would have done it in 6 minutes. If the air leaks out at a constant rate, then how long (in minutes) does it take for all the punctures together to make it flat?

Five men and 2 boys can do as much work in 30 days as 7 men and 10 boys can do in 15 days. How many boys should join 40 men to do the same work in 4 days?

A completes 20% of a work in 5 days and B completes one-third of the work in 5 days. They began the work together but B leaves after 3 days. The total number of days needed for completion of the work is:

A certain numberof persons can complete a work in 34 days working 9 hours a day. If the number of persons is decreased by 40%, then how many hours a day should the remaining persons work to complete the work in 51 days?