A man rowing at the rate of 5 km per hour in still water takes thrice, as much time in going 40 km up the river as in going 40 km down. Find the rate at which the river flows.

A motor boat whose speed is 18 km/hr in still water takes 1 hour more to go 24 km upstream than to return downstream to the same spot. Find the speed of the stream.

A river 3 m deep and 40 m wide is flowing at the rate of 2 km per hour. How much water will fall into the sea in a minute?

A motor boat whose speed is 15 km/hour in still water goes 30 km downstream and comes back in a total time of 4 hours 30 minutes. Find the speed of the stream.

A man can swim with a speed of 4.0 km//h in still water. How long does he take to cross a river 1.0 km wide if the river flows steadily at 3.0 km//h and he makes his strokes normal to the river current? How far down the river does he go when he reaches the other bank ?

The bottom of a rectangular swimming tank is 25 m by 40m. Water is pumped into the tank at the rate of 500 cubic metres per minute. Find the rate at which the level of water in the tank is rising.

In how much time will a train 250 m long, running at 50 km/hr pass a man, running at 5 km/hr in the same direction in which the train is going?

A man of height 2m walks at a uniform speed of 5km/h away from a lamp post which is 6m high. Find the rate at which the length of his shadow increases.