Richa travels from A to B at the speed of 15 km/h, from B to C at 20 km/h, and from C to D at 30 km/h. If AB = BC = CD, then find the Richa's average speed.

20 km/h

Given :-

Let AB = BC = CD = 60 km

Time for AB = \(\frac{60}{15}\) = 4 hours

Time for BC = \(\frac{60}{20}\) = 3 hours

Time for CD = \(\frac{60}{30}\) = 2 hours

Average Speed = \(\frac{60 + 60 + 60}{4 + 3 + 2}\)  = \(\frac{180}{9}\)

= 20 km/h