Question : A truck goes from Haryana to Bangalore with an average speed of 60 km/hr. The journey takes 30 hours. It returns from Bangalore to Haryana on the same road with an average speed of 40 km/hr. What was the average speed of the truck during the roundtrip?
Option 1: 60 km/hr
Option 2: 40 km/hr
Option 3: 50 km/hr
Option 4: 48 km/hr
Correct Answer: 48 km/hr
Solution :
The distance from Haryana to Bangalore = 60 km/hr × 30 hr = 1800 km
The truck returns on the same road, so the total distance of the round trip = 2 × 1800 km = 3600 km
Speed = $\frac{\text{Distance}}{{\text{Time}}}$
The time is taken for the return journey from Bangalore to Haryana = $\frac{1800}{40}$ = 45 hours
So, the total time for the round trip = 30 hours + 45 hours = 75 hours
Average speed = $\frac{\text{Total distance}}{{\text{Total time}}}$
The average speed of the truck during the round trip = $\frac{3600}{75}$ = 48 km/hr
Hence, the correct answer is 48 km/hr.
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