A man goes to Mumbai from Pune at a speed of 78km/hr and returns to Pune at speed of 91 km/hr, through same route. What is his average speed (in km/hr) of the entire journey?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is Option 4 i.e. 84.
Average speed = (2 × x × y) ÷ (x + y)
= (2 × 78 × 91) ÷ (78 + 91)
= (14196) ÷ 169
= 84 km/hr