Correct Answer - Option 1 : 36 km/hr

**Given:**

Suresh travels at a speed of 30 km/hr and returns back with a speed of 45 km/hr.

**Formula**:

If a and b are two different speed traveling the same distance,

then, Average speed = 2ab/(a + b);

**Calculation**:

According to the question,

Suresh travels the same distance at the speed of 30 km/hr and 45 km/hr.

Average Speed = (2 × 45 × 30)/(45 + 30)

⇒ 2700/75 = 36 km/hr

**∴** **The average speed of the whole journey is 36 km/hr.**