Correct Answer - Option 3 : 16.8 kmph
Given:
A man travels from place A to B and comes back. He goes at a speed of 21 kmph and returns at a speed of 14 kmph.
Formula Used:
When distance is equal, Average speed = 2 S1 × S2 / (S1 + S2)
Calculation:
Average speed for his whole journey = 2 × 21 × 14 / (21 +14)
= 2 × 21 × 14 × 1/35
= 16.8 kmph