A boat can row 15 km/h in still water. If the river current flows at 3 km/h, find the distance covered by the boat downstream in 20 minutes. MCQ with Answer and Explanation

A boat can row 15 km/h in still water. If the river current flows at 3 km/h, find the distance covered by the boat downstream in 20 minutes.
A. 5 km
B. 7 km
C. 6 km
D. 8 km
Answer: Option C
Solution (By JKSSB Mock Tests)
Downstream speed = 15 + 3 = 18 km/h. Time = 20 minutes = 20/60 = 1/3 hour. Distance covered = Speed * Time = 18 * (1/3) = 6 km.

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Practice More Time Speed and Distance Questions

Question #1
A dog spots a rabbit 200 meters away. The rabbit speeds off at 24 km/h and the dog pursues at 30 km/h. How much distance will the rabbit run before it is caught?
A. 900 meters
B. 850 meters
C. 800 meters
D. 750 meters

Correct Answer: Option C


Explanation:
Relative speed = 30 - 24 = 6 km/h = 6 * (5/18) = 5/3 m/s. Time to catch = 200 / (5/3) = 120 seconds. Distance run by rabbit = Speed * Time = [24 * (5/18)] * 120 = (20/3) * 120 = 800 meters.

This question belongs to: Maths Time Speed and Distance
Question #2
A man can walk a distance in 4 hours and ride back in 3 hours. If he walks both ways, he takes 8 hours. How much time will he take if he rides both ways?
A. 6 hours
B. 5 hours
C. 8 hours
D. 7 hours

Correct Answer: Option A


Explanation:
Let walking time one way be W and riding time one way be R. W + R = 7 hours. Walking both ways: 2W = 8 => W = 4 hours. Substituting W in first equation: 4 + R = 7 => R = 3 hours. Riding both ways: 2R = 2 * 3 = 6 hours.

This question belongs to: Maths Time Speed and Distance
Question #3
A train 150 meters long takes 20 seconds to cross a platform 250 meters long. Find the speed of the train in km/h.
A. 80 km/h
B. 50 km/h
C. 72 km/h
D. 64 km/h

Correct Answer: Option C


Explanation:
Total distance = 150 + 250 = 400 meters. Time = 20 seconds. Speed = 400 / 20 = 20 m/s. Speed in km/h = 20 * (18/5) = 72 km/h.

This question belongs to: Maths Time Speed and Distance