A man covers 1/3 of his journey by bus at 30 km/h, 1/3 by train at 60 km/h and the last 1/3 by scooter at 20 km/h. Find his average speed for the whole journey. MCQ with Answer and Explanation
A man covers 1/3 of his journey by bus at 30 km/h, 1/3 by train at 60 km/h and the last 1/3 by scooter at 20 km/h. Find his average speed for the whole journey.
A. 40 km/h
B. 25 km/h
C. 30 km/h
D. 35 km/h
Answer: Option C
Solution (By JKSSB Mock Tests)
Let each third of the journey be 60 km. Total distance = 3 * 60 = 180 km. Total time taken = 60/30 + 60/60 + 60/20 = 2 + 1 + 3 = 6 hours. Average speed = 180 / 6 = 30 km/h.
A vehicle covers a specific highway distance at 50 km/h. If it spikes its speed to 60 km/h, it clears the stretch 20 minutes early. Find the total distance.
Explanation:
Time difference = 20 minutes = 20/60 = 1/3 hours. Let distance be d. d / 50 - d / 60 = 1/3 => (6d - 5d) / 300 = 1/3 => d / 300 = 1/3 => d = 100 km.
Explanation:
Ratio of speeds = 3:5, so ratio of times taken = 5:3. Given 5 parts = 40 seconds => 1 part = 8 seconds. Time taken by the second runner = 3 parts = 3 * 8 = 24 seconds.
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