CAT 1999 — QA Question 16
Relative SpeedEasy
Navjivan Express from Ahmedabad to Chennai leaves Ahmedabad at 6.30 a.m. and travels at 50 kmph towards Baroda situated 100 km away. At 7.00 a.m. Howrah-Ahmedabad Express leaves Baroda towards Ahmedabad and travels at 40 kmph. At 7.30 a.m. Mr Shah, the traffic controller at Baroda realizes that both the trains are running on the same track. How much time does he have to avert a head-on collision between the two trains?
Answer & solution
- A
15 min
20 min
- C
25 min
- D
30 min
Solution
At 7.30 a.m., Navjivan Express is at 50 km from A at the same time, Howrah-Ahmedabad Express is at 20 km from B.
Hence, distance between the trains at 7.30 a.m. is 30 km.
Relative speed = 50 + 40 = 90 kmph
Hence, time left = hr = 20 min.
Hence, option (b).