Correct Answer - Option 3 : 72 km/hr
Given:
Speed for 5 km = 120 km/hr
Speed for nect 10 km = 60 km/hr
Formula used:
Average speed = Total Distance/Total time
Calculation:
Time to travel 5 km = (5/120) hr = 1/24 hr
Time to travel next 10 km = (10/60) hr = 1/6 hr
Total time taken = (1/24) + (1/6) = 5/24 hr
Total distance = (5 + 10) km = 15 km
Average speed = 15 ÷ (5/24) km/hr
⇒ 15 × (24/5) km/hr
⇒ 72 km/hr
∴ The average speed of the train is 72 km/hr
