A trained covered x km at 40 kmph and another 4x km at 20 kmph. Find the average speed of the train in covering the entire 3x km.  Choose the correct choice from the following answers:
A) 11.33 kmph	B) 12.33 kmph	C) 13.33 kmph	D) 14.33 kmph	E) 23.33 kmph
Total time taken = x/40 + 4x/20 hours   = 9x/40 hours   Average speed = 3x/(9x/40) = 13.33 kmph   ANSWER:13.33 kmph
<result>C</result>
A trained covered x km at 40 kmph and another 4x km at 20 kmph. Find the average speed of the train in covering the entire 3x km.