Ramesh covers one-fourth of the total distance at 30 km/hr, one-fourth at 20 km/hr and rest of his journey at 60 km/hr. Find Ramesh's average speed for the whole distance?

34.28 km/hr

Let the total distance = 120 km.   (Multiple of 4, 20, 30, 60)

Time taken in 1st one forth distance = \(\frac{\frac{120}{4}}{30}\) = \(\frac{30}{30}\) = 1hr

Time taken in 2nd one forth distance = \(\frac{\frac{120}{4}}{20}\) = \(\frac{30}{20}\) = 1.5 hr

Remaining distance = 120 - 60 = 60 km.

Time taken in rest distance = \(\frac{60}{60}\) = 1 hr

Total time taken = 1 + 1.5 + 1 = 3.5 hrs.

Average Speed = \(\frac{Total\;distance}{total\;time}\) =  \(\frac{120}{3.5}\) = 34.28 km/hr