Question 76
A person goes from town A to town B with a speed of 60 km/h and return to A with a speed of 40 km/h. His average speed for the whole journey is
Solution
Average speed is the harmonic mean of both speeds = $$2\div(\frac{1}{60}+\frac{1}{40})$$
= $$2\div(\frac{2+3}{120})$$
= $$2\times\frac{120}{5}=48$$ km/hr
=> Ans - (B)
