This is the interview puzzle asked to my friend in an interview of "blackrock".
As shown in the picture below, There is a circular car race track of 10km. There are two cars, we called them Car A and Car B. And they are at the exact opposite end to each other. At Time T(0), Both cars move toward each other at a constant speed of 100m / seconds. As we know both cars are at the same speed they will always be the exact opposite to each other.
Note, at the center, there is a bug which starts flying towards Car A at time T(0). When the bug reaches car B, it turns back and starts moving towards the car A. The speed of bug is 1m/second. After 5hours all three stop moving.
What is the total distance covered by the bug?

As we know bug travels at a constant speed of 1m/seconds
=> in 5 hours
=> 5 * 60 * 60 meters
=> 18km.