# GATE | GATE CS 2019 | Question 5

• Last Updated : 13 Feb, 2019

Two cars at the same time from the same location and go in the same direction. The speed of the first car is 50 km/h and the speed of the second car is 60 km/h. The number of hours it takes for the distance between the two cars to be 20 km is _________.

Note: This was Numerical Type question.
(A) 1
(B) 2
(C) 3
(D) 6

Explanation: Given two cars at the same time from the same location and go in the same direction with speed of 50 km/h and 60 km/h.

Therefore, after 1 hour,

```distance traveled by first car (with speed of 50 km/h) = 50*1 = 50 km
And, distance traveled by second car (with speed of 60 km/h) = 60*1 = 60 km

So, distance between these cars = 60 - 50 = 10 km ```

After 2 hour,

```distance traveled by first car (with speed of 50 km/h) = 50*2 = 100 km
And, distance traveled by second car (with speed of 60 km/h) = 60*2 = 120 km

So, distance between these cars = 120 - 100 = 20 km ```

Alternative way:

```→ (distance traveled by second car) - (distance traveled by first car) = 20 km
→ (S2*T) - (S1*T) = 20
→ (60*T) - (50*T) = 20
→ 10*T = 20
→ T = 2 ```

Therefore, option (B) is correct.

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