A cistern can be filled by a tap in 6 hours and emptied by an outlet pipe in 8 hours. How long will it take to fill the cistern if both the tap and the pipe are opened together ?

A cistern can be filled by one tap in 4 hours and by another in 3 hours. How long will it take to fill it if both taps are opened together ?

10 boys can dig a pitch in 12 hours. How long will 8 boys take to do it?

One tap can fill a cistern in 3 hours and the waste pipe can empty the full cistern in 5 hours. In what time will the empty cistern be full, if the tap and the waste pipe are kept open together ?

If 6 oil tankers can be filled by a pipe in 4 1/2 hours, how long does the pipe take to fill 4 such oil tankers?

Because of anticipated heavy rain , the water level in a swimming pool must be lowered by 1 foot . Opening drain A lowers the level by 1 foot in 4 hours , whereas opening the smaller drain B does the job in 6 hours . How long will it take to lower the water level by 1 foot if both drains are opended ? An equation that solves the problem is

12 pipes, all of the same size, fill a tank in 42 minutes. How long will it take to fill the same tank,if 21 pipes of the same size are used ?

A cistern has two inlets A and B which can fill it in 12 hours and 15 hours respectively. An outlet can empty the full cistern in 10 hours. If all the three pipes are opened together in the empty cistern, how much time will they take to fill the cistern completely?

6 pipes are required to fill a tank in 1 hour 20 minutes. How long will it take if only 5 pipes of the same type are used?

Two hoses are pouring water into an empty pool. Hose 1 alone would fill up the pool in 6 hours. Hose 2 alone would fill up the pool in 4 hours. How long would it take for both hoses to fill up two - thirds of the pool?

If 7 workers can assemble a car in 8 hours, how long would it take 12 workers to assemble the same car?