One-fourth of certain journey is covered at the rate of 25 km/h, one-third at the rate of 30 km/h and the rest at 50 km/h. Find the average speed for the whole journey. Pick one
A) 600/53km/h	B) 1200/53 km/h	C) 1800/53 km/h	D) 1600/53 km/h	E) None of these
Solution: Let distance be 120 KM, hence 30 KM is covered by @ 25 kmph and 40 km covered by @ 30 kmph and rest 50 km has been covered@ 50 km.   Now, average = (120/total time taken);   = {120/[(30/25)+(40/30)+(50/50)}]   = 3600/106 = 1800/53 km/h.   Answer: Option 1800/53 km/h
<result>C</result>
One-fourth of certain journey is covered at the rate of 25 km/h, one-third at the rate of 30 km/h and the rest at 50 km/h. Find the average speed for the whole journey.