QA – Placement Quizzes | Trains, Boats and Streams | Question 5
A motorboat crosses a certain distance in 1 hour and comes back in 1½ hours. If the stream is running at 3 km/h, find out the speed of motorboat in still water.
(A) 10 km/h
(B) 15 km/h
(C) 12 km/h
(D) None of these
Explanation: Let the speed of motorboat in still water be x km/h. Then,
Downstream speed = (x + 3) km/h.
Upstream speed = (x – 3) km/h.
Then, (x + 3) × 1 = (x – 3) × 3/2
⇒ 2x + 6 = 3x – 9
⇒ x = 15.
So, the speed of motorboat in still water is 15 km/h.
Quiz of this Question
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