A boatman rows 30 km downstream and 18 km upstream, taking 3 hours for each leg of the journey. Find the speed of the boat in still water. MCQ with Answer and Explanation

A boatman rows 30 km downstream and 18 km upstream, taking 3 hours for each leg of the journey. Find the speed of the boat in still water.
A. 10 km/h
B. 9 km/h
C. 7 km/h
D. 8 km/h
Answer: Option D
Solution (By JKSSB Mock Tests)
Downstream speed = 30 / 3 = 10 km/h. Upstream speed = 18 / 3 = 6 km/h. Speed in still water = (10 + 6) / 2 = 8 km/h.

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Practice More Time Speed and Distance Questions

Question #1
A person walks from his home to his shop at a speed of 5 km/h and arrives 6 minutes early. If he walks at 4 km/h, he arrives 6 minutes late. Find the distance between his home and shop.
A. 6 km
B. 4 km
C. 5 km
D. 3 km

Correct Answer: Option B


Explanation:
Time difference = 6 - (-6) = 12 minutes = 12/60 = 1/5 hour. Let distance be d. d/4 - d/5 = 1/5 => d/20 = 1/5 => d = 4 km.

This question belongs to: Maths Time Speed and Distance
Question #2
Walking at 3/4 of his normal speed, a person is 10 minutes late to his destination. What is his normal time?
A. 30 minutes
B. 35 minutes
C. 40 minutes
D. 25 minutes

Correct Answer: Option A


Explanation:
New speed = 3/4 of normal speed => New time = 4/3 of normal time. Difference = 1/3 of normal time = 10 minutes. Normal time = 10 * 3 = 30 minutes.

This question belongs to: Maths Time Speed and Distance
Question #3
Walking at 5/6 of his usual speed, a man reaches his destination 15 minutes late. Find his usual time.
A. 70 minutes
B. 85 minutes
C. 75 minutes
D. 80 minutes

Correct Answer: Option C


Explanation:
New speed = 5/6 of usual speed => New time = 6/5 of usual time. Difference = 1/5 of usual time = 15 minutes. Usual time = 15 * 5 = 75 minutes.

This question belongs to: Maths Time Speed and Distance