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