A car covers 60 km at a speed of 84 km/h. If the average speed for the whole journey is72 km/h, then the speed of the car for the next 60 km of the journey is:

Correct option is A

If the distance is same, then average speed = $$\frac{2 S_1 S_2}{S_1 +S_2}$$

72= $$\frac{2×84× S_2}{84 +S_2}$$​

$$72×84 + 72 S_2= 2×84×S_2\\72×84= 96S_2\\S_2 = 63 km/hr$$​​