A boat goes 20 km downstream in one hour and the same distance upstrea

1.	A boat goes 20 km downstream in one hour and the same distance upstream in two hours. What is the speed of the boat in still water?
Answer» Let the speed of the boat in still water be \(x\) km/hr and speed of the stream = y km/hr Then, speed of boat downstream = (\(x\) + y) km/hr Speed of boat upstream = (\(x\) – y) km/hr Given (\(x\) + y) × 1 = 20 and (\(x\) – y) × 2 = 20 ⇒ \(x\) + y = 20 …(i) and \(x\) – y = 10 …(ii) Adding eqn (i) and (ii), we get 2\(x\) = 30 ⇒ \(x\) = 15 km/hr.

A boat goes 20 km downstream in one hour and the same distance upstream in two hours. What is the speed of the boat in still water?

Answer»

Let the speed of the boat in still water be \(x\) km/hr and speed of the stream = y km/hr

Then, speed of boat downstream = (\(x\) + y) km/hr

Speed of boat upstream = (\(x\) – y) km/hr

Given (\(x\) + y) × 1 = 20 and (\(x\) – y) × 2 = 20

⇒ \(x\) + y = 20 …(i) and \(x\) – y = 10 …(ii)

Adding eqn (i) and (ii), we get

2\(x\) = 30 ⇒ \(x\) = 15 km/hr.

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A boat goes 20 km downstream in one hour and the same distance upstream in two hours. What is the speed of the boat in still water?

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