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A boatman can go certain distance downstream in 2 hrs. and upstream same distance in 3 hrs. If the stream flow at the speed of 4 km/h, find the speed of boat in still water.

A8 km/h

B12 km/h

C20 km/h

D10 km/h

Answer:

C. 20 km/h

Read Explanation:

Let the speed of the boat in still water is B km/h. Since he is traveling the same distance upstream and downstream; (B + 4)×2 = (B − 4)×3 ⇒ 2B + 8 = 3B ⇒ B = 8 + 12 ⇒ B = 20 km/hr


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