# QA – Placement Quizzes | Trains, Boats and Streams | Question 1

A boatman takes 3 hours 45 minutes to travel 15 km downstream and takes 2 hours 30 minutes to travel 5 km upstream of a river. What is the speed of the stream of the river in km/h?**(A)** 2 km/h**(B)** 1 km/h**(C)** 6 km/h**(D)** 4 km/h**Answer:** **(B)****Explanation:** Downstream:

Time taken = 3 + 45/60 = 3 + 3/4 = 15/4 h.

Distance covered = 15 km.

Downstream Speed = 15 / (15/4) = 4 km/h.

Upstream:

Time taken = 2 + 30/60 = 2 + 1/2 = 5/2 h.

Distance covered = 5 km.

Upstream Speed = 5 / (5/2) = 2 km/h.

We know, speed of stream = 1/2 (Downstream Speed – Upstream Speed) = 1/2 (4-2) = 1 km/h.

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