Question

Places P and Q are 100km apart on highway. One car starts from P and another from Q at the same time. If the cars travel in the same direction at different speeds, they meet in 5 hours. If they travel towards each other, they meet in 1 hour. What are the speeds of the two cars?

Answer 1

Let speed of faster car = x Km/ h

Speed of slower car = y km /h

Relative speed when both car travels in same direction = x - y

If the cars travel in the same direction at different speeds, they meet in 5 hours

Speed = distance/ time

Total distance = 100 km

Speed x – y = 100/5

X – y = 20

Add y both side we get

X = 20 + y …(1)


Relative speed when both car travels in opposite direction = x + y



If they travel towards each other, they meet in 1 hour



.Speed = distance/ time


Total distance = 100 km

Speed x + y = 100/1


Plug the value of x form equation 1 we get

20 + y + y = 100

2y = 80Y = 40

Plug the value of y in equation 1 we get

X = 20 + 40X = 60


Hence speeds are 40 Km /h and 60 Km /h