A motorboat covers a certain distance downstream in 4 hours and covers the same distance upstream in 5 hours. If the speed of the stream is 2 km/h, find the speed of the motorboat in still water. MCQ with Answer and Explanation

A motorboat covers a certain distance downstream in 4 hours and covers the same distance upstream in 5 hours. If the speed of the stream is 2 km/h, find the speed of the motorboat in still water.
A. 22 km/h
B. 15 km/h
C. 18 km/h
D. 20 km/h
Answer: Option C
Solution (By JKSSB Mock Tests)
Let speed of boat in still water be v. Downstream speed = v + 2, Upstream speed = v - 4. Distance is same, so 4(v + 2) = 5(v - 2) => 4v + 8 = 5v - 10 => v = 18 km/h.

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Practice More Time Speed and Distance Questions

Question #1
A train 120 meters long passing a warehouse platform 280 meters long takes exactly 20 seconds. Find the velocity index of the train in km/h.
A. 84 km/h
B. 72 km/h
C. 64 km/h
D. 80 km/h

Correct Answer: Option B


Explanation:
Total distance = 120 + 280 = 400 meters. Speed = 400 / 20 = 20 m/s. In km/h = 20 * (18/5) = 72 km/h.

This question belongs to: Maths Time Speed and Distance
Question #2
A train running at 72 km/h overtakes a cyclist riding at 12 km/h in the same direction in 12 seconds. Find the length of the train.
A. 180 meters
B. 200 meters
C. 220 meters
D. 240 meters

Correct Answer: Option B


Explanation:
Relative speed = 72 - 12 = 60 km/h = 60 * (5/18) = 50/3 m/s. Length of train = Relative speed * Time = (50/3) * 12 = 200 meters.

This question belongs to: Maths Time Speed and Distance
Question #3
A motorboat registers a speed of 15 km/h in still water. It takes 4 hours to cover a certain distance upstream. If the stream velocity is 3 km/h, find the distance covered.
A. 52 km
B. 48 km
C. 44 km
D. 56 km

Correct Answer: Option B


Explanation:
Upstream speed = 15 - 3 = 12 km/h. Distance = Upstream speed * Time = 12 * 4 = 48 km.

This question belongs to: Maths Time Speed and Distance