A train of 40 carriages, each of 60 meters length, when an engine also of 60 meters length is running at a speed of 60 kmph. In what time will the train cross a bridge 1.5 km long?  Choose the correct choice from the following answers.
A) 6
B) 3
C) 4
D) 3.9
E) 3.6

Rationale: d = 40 * 60 + 1500 = 3900 m t = 3900 / 60 * 18 / 5 = 234 sec = 3.9 mins answer : d
Answer: D