Trains Boats and Streams Practice Test 1 with solutions

Question : 27 of 40

Marks: +1, -0

A boat goes 6 km upstream and back to the starting point in 2 hours. If the current of the stream runs at the rate of 4 km/hr, find the speed of the boat in still water.

6 km/hr
8 km/hr
10 km/hr
12 km/hr

Validate

Solution:

Let the speed of a boat in still water = x km/hr; then

6/{x-4}+6/{x+4}

= 2
⇒

{2x}/{x^2-16}

1/3

⇒

x^2

- 6x - 16 = 0
⇒ (x - 8) (x + 2) = 0
Hence, the speed of the boat = 8 km/hr

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