Vikas covered a certain distance by bike. If he covers 40% of the distance at 40 km/h, 50% of the distance at 25 km/h and the remaining 10% distance at 10 km/h. Find his average speed over the whole distance.

25 km/h

Let total distance = 100 km

Distance 1 = 40% of 100 = 40

Time 1 = \(\frac{40}{40}\) = 1 hour

Distance 2 = 50% of 100 = 50

Time 2 = \(\frac{50}{25}\) = 2 hour

Distance 3 = 10% of 100 = 10

Time 3 = \(\frac{10}{10}\) = 1 hour

Average speed = \(\frac{100}{1+2+1}\)

= \(\frac{100}{4}\)

= 25 km/h