The average speed of a train running at a speed of 30 km/hr during the first 100 kilometres, at 40 km/hr during the second 100 kilometres and at 50 km/hr during the last 100 kilometres is nearly?
Answers
A) 38.5 km/hr  B) 38.3 km/hr  C) 40.0 km/hr  D) 39.2 km/hr  E) None of these
Time taken to cover first 100 kilometres = 100/3 = 3(1/3) hours   Time taken to cover second 100 kilometres =100/40 = 2(1/2) hours   Time take to cover last 100 kilometres = 100/2 = 2 hours   Total distance covered = 300 km.   Total time taken = 47/6 hours   Thus, average speed = 300/(47/6) = 38.3 km/hr.   ANSWER:38.3 km/hr
<result>B</result>
The average speed of a train running at a speed of 30 km/hr during the first 100 kilometres, at 40 km/hr during the second 100 kilometres and at 50 km/hr during the last 100 kilometres is nearly?