Question

Places A and B are 100km apart on the highway. One car starts from A and another from B at the same time. If the car travel in same direction at a different speed, they meet in 5hrs. If they travel towards each other, they meet in 1hr. What are the speeds of the two cars?

Answer 1

Sol:
Let the speeds of the cars be x km/hr and y km/hr

Case 1:
When the cars are going in the same direction
Relative speed = x - y
Distance = 100 km
Time = 100 / (x - y) = 5 hrs
x - y = 100 / 5=20
x – y = 20 ------------- (1)

Case 2:
When the cars are going in the opposite direction
Relative speed = x + y
Time =100 / (x + y) = 1 hrs
x + y = 100 ------------- (2)

Solving the equations (1) and (2),
x = 60
y = 40
Hence the speeds of the cars are 60 km/hr and 40 km/hr.