A boatman rows 1 km in 5 minutes along the stream and 1 km in 12 minutes against the stream. Find the speed of the stream. MCQ with Answer and Explanation

Question

A boatman rows 1 km in 5 minutes along the stream and 1 km in 12 minutes against the stream. Find the speed of the stream.

A. 4.5 km/h

B. 4 km/h

C. 3.5 km/h

D. 5 km/h

Answer: Option C

Solution (By JKSSB Mock Tests)

Downstream speed = 1 km / (5/60 hours) = 12 km/h. Upstream speed = 1 km / (12/60 hours) = 5 km/h. Speed of stream = (Downstream speed - Upstream speed) / 2 = (12 - 5) / 2 = 3.5 km/h.

This question belongs to: Maths Time Speed and Distance

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Question #1

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Excluding institutional stops, the speed of an intercity coach is 72 km/h and including stops it is 60 km/h. For how many minutes does the coach stop per hour?

A. 15 minutes

B. 12 minutes

C. 10 minutes

D. 8 minutes

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Correct Answer: Option C

Explanation:
Stoppage time per hour = (72 - 60) / 72 = 12 / 72 = 1/6 hour. In minutes = (1/6) * 60 = 10 minutes.

This question belongs to: Maths Time Speed and Distance

Question #2

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A standard boat covers 12 km upstream in 4 hours and 16 km downstream in 2 hours. What is the speed of the boat in still water?

A. 6.5 km/h

B. 7 km/h

C. 6 km/h

D. 5.5 km/h

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Correct Answer: Option D

Explanation:
Upstream speed = 12 / 4 = 3 km/h. Downstream speed = 16 / 2 = 8 km/h. Speed in still water = (Downstream speed + Upstream speed) / 2 = (8 + 3) / 2 = 5.5 km/h.

This question belongs to: Maths Time Speed and Distance