A sound wave travels at 340 m/s. How much distance in kilometers does it cover in 20 seconds? MCQ with Answer and Explanation

A sound wave travels at 340 m/s. How much distance in kilometers does it cover in 20 seconds?
A. 6.5 km
B. 7.2 km
C. 7.5 km
D. 6.8 km
Answer: Option D
Solution (By JKSSB Mock Tests)
Distance = Speed * Time = 340 * 20 = 6800 meters. Converting to kilometers = 6800 / 1000 = 6.8 km.

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Practice More Time Speed and Distance Questions

Question #1
A motorboat covers a certain distance downstream in a river in 3 hours and returns upstream in 4 hours. If the speed of the river current is 3 km/h, find the speed of the motorboat in still water.
A. 24 km/h
B. 27 km/h
C. 21 km/h
D. 18 km/h

Correct Answer: Option C


Explanation:
Let speed of boat in still water be v. Downstream speed = v + 3, Upstream speed = v - 3. Distance is same, so 3(v + 3) = 4(v - 3) => 3v + 9 = 4v - 12 => v = 21 km/h.

This question belongs to: Maths Time Speed and Distance
Question #2
A man walks from his sector quarters to a focal workshop at 4 km/h and arrives 15 minutes late. If he scales his speed to 6 km/h, he arrives 5 minutes early. Find the distance.
A. 5.0 km
B. 4.5 km
C. 4.0 km
D. 3.5 km

Correct Answer: Option C


Explanation:
Time difference = 15 - (-5) = 20 minutes = 20/60 = 1/3 hours. Let distance be d. d/4 - d/6 = 1/3 => d/12 = 1/3 => d = 4 km.

This question belongs to: Maths Time Speed and Distance
Question #3
A motorboat rows 30 km downstream in 3 hours and tracks the identical route upstream back to the jetty point in 6 hours. Find the net speed index of the current stream flow.
A. 2.0 km/h
B. 3.5 km/h
C. 2.5 km/h
D. 3.0 km/h

Correct Answer: Option C


Explanation:
Downstream speed = 30 / 3 = 10 km/h. Upstream speed = 30 / 6 = 5 km/h. Speed of current stream flow = (10 - 5) / 2 = 5 / 2 = 2.5 km/h.

This question belongs to: Maths Time Speed and Distance