Two pipes A and B can fill a tank in 20 minutes and 30 minutes respectively. If both pipes are opened together, how much time will they take to fill the tank?
If 6 men and 8 boys can do a piece of work in 10 days, while 26 men and 48 boys can do the same in 2 days, what is the time taken by 15 men and 20 boys?
A cistern has two taps which fill it in 12 and 15 minutes respectively. There is also a waste pipe. When all three are opened, the cistern is filled in 20 minutes. How long will the waste pipe take to empty it?
A train passes a station platform in 36 seconds and a man standing on the platform in 20 seconds. If the speed of the train is 54 km/h, what is the length of the platform?