A trained covered x km at 70 kmph and another 2x km at 20 kmph. Find the average speed of the train in covering the entire 3x km.
Choose the correct option:
A) 22.25
B) 99
C) 26.25
D) 66
E) 887

Rationale: "total time taken = x / 70 + 2 x / 20 hours = 4 x / 35 hours average speed = 3 x / ( 4 x / 35 ) = 26.25 kmph answer : c"
Answer: C