A boat rowed downstream covers 40 km in 4 hours and manages 20 km upstream in 4 hours. Find the baseline speed of the boat in still water. MCQ with Answer and Explanation

Question

A boat rowed downstream covers 40 km in 4 hours and manages 20 km upstream in 4 hours. Find the baseline speed of the boat in still water.

A. 8.0 km/h

B. 7.0 km/h

C. 7.5 km/h

D. 8.5 km/h

Answer: Option C

Solution (By JKSSB Mock Tests)

Downstream speed = 40 / 4 = 10 km/h. Upstream speed = 20 / 4 = 5 km/h. Speed in still water = (10 + 5) / 2 = 7.5 km/h.

This question belongs to: Maths Time Speed and Distance

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Question #1

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Excluding operational station stops, a city bus routes at an average of 42 km/h, and including stops its net average speed is 35 km/h. For how many minutes does it stop per hour?

A. 14 minutes

B. 12 minutes

C. 10 minutes

D. 8 minutes

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Correct Answer: Option C

Explanation:
Stoppage time per hour = (42 - 35) / 42 = 7 / 42 = 1/6 hour = 10 minutes.

This question belongs to: Maths Time Speed and Distance

Question #2

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A cyclist travels at a speed of 12 km/h for the first 10 km and at a speed of 10 km/h for the next 12 km. Find his average speed for the entire trip.

A. 11.00 km/h

B. 10.45 km/h

C. 11.24 km/h

D. 10.83 km/h

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Correct Answer: Option D

Explanation:
Total distance = 10 + 12 = 22 km. Total time taken = 10/12 + 12/10 = 5/6 + 6/5 = (25 + 36) / 30 = 61 / 30 hours. Average speed = 22 / (61/30) = 660 / 61 = 10.82 hours (approx 10.83 km/h).

This question belongs to: Maths Time Speed and Distance