Correct Answer - Option 2 : 2,100/13 km
Given:
The car travelled a certain distance at 60 km/hr and returned at 70 km/hr
Total time taken by car to cover the total distance is 5 hours.
Concepts used:
Speed = Distance/Time
Average speed = (2S1 × S2)/(S1 + S2)
Where,
S1 → Speed at which car travelled a certain distance
S2 → Speed at which car returned to cover the same distance.
Calculation:
Let the distance travelled be x km.
Total distance covered in travelling a certain distance and returning to cover the same distance
Total distance = x + x km = 2x km
Total time taken by car to cover the total distance is 5 hours.
Speed = Distance/Time
⇒ Speed = 2x/5 km/hr
Average speed = 2S1 × S2/(S1 + S2)
⇒ 2x/5 km/hr = 2 × 60 × 70/(60 + 70)
⇒ x = 8,400 × 5/130 × 2
⇒ x = 2,100/13
∴ Distance covered by car is (2,100/13) km.
