Question

A man travels from town P to town Q at 30 km/h and returns along the same road at 60 km/h. What is his average speed for the whole journey?

• A. 40 km/h
• B. 45 km/h
• C. 48 km/h
• D. 50 km/h

Hint:

For equal distances use the harmonic mean, not the simple average.

Answer 1

The Correct Option is A

Take the one-way distance as $60$ km. Time out $= \dfrac{60}{30} = 2$ h, time back $= \dfrac{60}{60} = 1$ h. Average speed $= \dfrac{120}{3} = 40$ km/h.