A man rows downstream 40 km in 4 hours and upstream 24 km in 4 hours. What is the speed of the stream? MCQ with Answer and Explanation

A man rows downstream 40 km in 4 hours and upstream 24 km in 4 hours. What is the speed of the stream?
A. 3 km/h
B. 4 km/h
C. 1 km/h
D. 2 km/h
Answer: Option D
Solution (By JKSSB Mock Tests)
Downstream speed = 40 / 4 = 10 km/h. Upstream speed = 24 / 4 = 6 km/h. Speed of stream = (Downstream speed - Upstream speed) / 2 = (10 - 6) / 2 = 2 km/h.

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Practice More Time Speed and Distance Questions

Question #1
A train passes a pedestrian standing on a platform in 6 seconds and passes the platform itself, which is 150 meters long, in 11 seconds. Find the speed of the train in km/h.
A. 90 km/h
B. 120 km/h
C. 108 km/h
D. 135 km/h

Correct Answer: Option C


Explanation:
Time taken to cross the platform alone = 11 - 6 = 5 seconds. Speed of train = 150 / 5 = 30 m/s. In km/h = 30 * (18/5) = 108 km/h.

This question belongs to: Maths Time Speed and Distance
Question #2
Two points P and Q are 240 km apart. Train A starts from P towards Q at 60 km/h at 9:00 AM. Train B starts from Q towards P at 80 km/h at 10:00 AM. At what time will they meet?
A. 11:45 AM
B. 11:17 AM
C. 11:00 AM
D. 11:30 AM

Correct Answer: Option B


Explanation:
By 10:00 AM, Train A covers 60 km. Remaining distance = 240 - 60 = 180 km. Relative speed = 60 + 80 = 140 km/h. Time to meet after 10 AM = 180 / 140 = 9/7 hours = 1 hour and 17 minutes. Meeting time is 11:17 AM.

This question belongs to: Maths Time Speed and Distance
Question #3
A sedan covers a distance path of 480 km at a uniform tracking speed. If the speed index is lowered by 10 km/h, the trip records 2 hours longer. Find the original baseline speed.
A. 60 km/h
B. 45 km/h
C. 55 km/h
D. 50 km/h

Correct Answer: Option D


Explanation:
Let original speed be s. 480 / (s - 10) - 480 / s = 2 => 240 / (s - 10) - 240 / s = 1 => 2400 = s(s - 10). Solving s^2 - 10s - 2400 = 0 gives (s - 50)(s + 40) = 0. Baseline speed = 50 km/h.

This question belongs to: Maths Time Speed and Distance