Mike took a bus from home to market, that travels at 30 kmph. While walking back at 6 kmph,
halfway through, he suddenly realized he was getting late and he cycled back the remaining distance in 20 kmph. Find the average speed.
Choose the correct choice
A) 21.2 kmph B) 12.1 kmph C) 23.4 kmph D) 20.4 kmph E) none of these

Rationale: let the distance be 2 x ( one way ) time taken by bus = 2 x / 30 , by walking = x / 6 , by cycling = x / 20 hours : . average speed = total distance / total time = 6 x / x / 15 + x / 6 + x / 20 = 6 * 60 / 4 + 10 + 3 = 21.2 answer : a
Answer: A