Question

Suresh travels to office at a speed of 30 km/hr and on his way back, he travels at a speed of 45 km/hr. Find the average speed of the whole journey?

1. 36 km/hr
2. 40 km/hr
3. 30 km/hr
4. 33 km/hr

Answer 1

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.