Important Sums on Streams – Upstream / Downstream
When we talk about the speed of the boat or swimmer, we mean the speed of the boat ( or swimmer) in still water. If the boat moves against the stream, it is called upstream and if it moves with the stream, we call it downstream.
Check some of the Sums/ Questions based on Streams –
Q. 1 The current of a stream runs at the rate of 4 km an hour. A boat goes 6 km and back to the starting point in 2 hours. The speed of the boat in still water shall be —
Q. 2. A boat covers 24 km upstream and 36 km downstream in 6 hours, while it covers 36 km upstream and 24 km downstream in 6.5 hours. The speed of the current shall be –
Q. 3. A boat goes 40 km upstream in 8 hours and 36 km downstream in 6 hours. What is the speed of the boat in still water ?
Q. 4. A man rows upstream 16 km and downstream 28 km, taking 5 hours each time. What is the velocity of the current ?
Q. 5. John can row a certain distance downstream in 6 hours and return the same distance in 9 hours. If the stream flows at the rate of 3 km per hour, then find the speed of John in still water.
Q. 6. A man can row 30 km upstream and 44 km downstream in 10 hours. He can also row 40 km upstream and 55 km downstream in 13 hours. Find the rate of the current and the speed of the man in still water.
Q. 7. A boy can row 6 km/ hour in still water. It takes him twice as long to row up as to row down the river. Find the rate of the stream.
Answers – 1 8 km/hour 2. 2 km/ hour 3. 5.5 km/hour 4. 1.2 km/hour 5. 15 km/hour 6. 3 km/hour 7. 2 km/hour
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