Question

A man travels a certain distance at a speed of 40 kmph and returns by increasing his speed by 50%. What is his average speed for the whole journey?
1. 50 kmph
2. 46 kmph
3. 48 kmph
4. 52 kmph

Answer 1

Correct Answer - Option 3 : 48 kmph

Given 

Speed of train in starting = 40 km/hr 

Formula Used 

Average speed = 2 × S₁ × S₂/(S₁ + S₂)

Calculation 

Speed of return journey = 40 + 40 × 50/100 = 60 km/hr

Average speed = 2 × 40 × 60/100 = 48 km/hr

∴ The average speed of man is 48 km/hr 

This formula is used only when the distance covered is same for both cases.