A motorist travels to a place 150 km away at an average speed of 50 km/hr and returns at 30 km/hr. His average speed for the whole journey in km/hr is :

35
36
37.5
38.2

Correct Answer: 37.5

Explanation:

Average speed = (2xy) /(x + y) km/hr

= (2 * 50 * 30) / (50 + 30) km/hr.

37.5 km/hr.

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