A boy in a train notices that he can count 31 telephone posts in 60 seconds. the distance between two posts is 60 meters. Calculate the speed of the train?
50 litre mixture of water and alcohol contains 10% alcohol. How much more alcohol must be added to make the strength of alcohol 40% in the new mixture?
Atul can do a piece of work in 18 days, Aaravya is 50% more efficient than Atul. How much more time does Atul take than Aaravya to do the same piece of work?