Correct Answer - Option 2 : 40.32 km/hour
Given
A person covered the distance in 2 hours = 30 km
A person covered the distance in 1and half hours = 40 km
A person covered the distance in 40 minutes = 20m/sec
Calculation
Distance covered by a person in the first 2 hours at a speed of 30 km/hr. = 2 × 30 = 60 km
Distance covered by a person in the next 1 and half hours at a speed of 40 km/hr. = 40 × 3/2 = 60 km
Distance covered in next 40 minutes at a speed of (20 m/sec) 72 km/hr. = 72 × 2/3 = 48 km [Hence, 20 × 18/5] = 72 km/hr
Total distance covered by the person 60 + 60 + 48 = 168 km
Total time taken = 2 + 3/2 + 2/3
⇒ 25/6 hr.
Average speed = 168 × 6/25 = 1008/25 = 40.32 km/hr
∴ The average speed is 40.32 km/hr
