Question

16. A man can row 40 kmph in still water and the river is running at 10 kmph. If the man takes 1 hr to row to a place and back, how far is the place?

Answer 1

Let the distance be x

Speed upstream = (40 - 10) = 30 kmph

Speed downstream = (40 + 10) = 50 kmph

Total time taken = 1 hr

x50+x30=1⇒

8x150=1⇒

x=150/8

= 18.75 km

Answer 2

Concept:

Distance = Speed × Time

Given:

We are given that:

A man can row 40 km/h in still water

The river is running at 10 km/h.

Find:

We need to find that how far is the place that is the distance between the starting point and that place.

Step-by-step explanation:

Let the distance be x

Speed upstream = (40 - 10) = 30 km/h

Speed downstream = (40 + 10) = 50 km/h

Total time taken = 1 hour

ATQ:

x / 50 + x / 30 = 1

8x / 150 = 1

x = 150 / 8

= 18.75 km

Therefore, the place is 18.85 km far away.

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