Ram travels a certain distance at 3 km/hr and reaches 15 min late. If he travels at 4 km/hr he reaches 15 min earlier. The distance he has to travel is?
Correct Answer: 6 km.
Explanation:
Let the distance be x km.
Then, x/3 - x/4 = 30/60
⇒ (4x - 3x ) / 12 = 1/2
∴ x = 6 km.