Question

While travelling in the same direction, a car overtakes another car in 5 seconds. While moving in the opposite direction, they cross each other in 2 seconds. What is the ratio of their speeds?

• A. Cannot be determined as their lengths is not given
• B. Cannot be determined as the starting points are not given
• C. 7:3
• D. 5:2

Answer 1

The correct option is C 7:3

Let the speed of the first car be F units per second and that of the second car be S units per second.

Let the combined length of the two cars be L units.

According to the question,

While moving in the same direction,

5(F – S) = L (1)

Similarly, while moving in the opposite direction,

2(F + S) = L (2)

From (1) and (2), we get

5(F – S) = 2(F + S)

⇒ 5F – 5S = 2F + 2S

⇒ 3F = 7S

⇒ F:S = 7:3

Hence, option C is the correct answer.