Two trains are moving in opposite directions at 60 km/hr and 90 km/hr. Their lengths are 1.10 km and 0.65 km respectively. The time taken by the slower train to cross the faster train in seconds is?  Choose the correct choice from the following answers
A) 42  B) 77  C) 48  D) 99  E) 11

Rationale: relative speed = 60 + 90 = 150 km / hr . = 150 * 5 / 18 = 125 / 3 m / sec . distance covered = 1.10 + 0.65 = 1.75 km = 1750 m . required time = 1750 * 3 / 125 = 42 sec . answer : a
Answer: A