A boat can travel 30 km upstream in a river in the same time as it takes to travel 50 km downstream. If the rate of stream is 5 kmph, then the speed of the boat in still water is ____ kmph.

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Detailed Solution

Concept- The speed of the boat in still water is 20 kmph.
To solve this question, we will consider the speed of the boat to be

kmph. As the rate of the stream is given in the question i.e., 5 kmph, we will have to add or subtract this speed of stream to the speed of the boat putting signs according to upstream and downstream and form an equation based on the time condition, also, provided in the question. Solving for

will give us our required answer.
We need to know one more thing, that is, the relation Between Speed, Distance and Time:

Upstream speed of the boat is

kmph and downstream speed of the boat is

.
Given condition in the question is that, the boat travels 30 km upstream in a river in the same period of time as it takes to travel 50 km downstream, i.e.,
Question Image

Hence, the correct answer is 20 Kmph.

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