Rohit misses his school bus and asks his father to drop him to school in his car. If his school is 10 km away and he has to reach there in exactly 15 minutes, at what speed (in km/hr) should his father drive?

 As per the given situation in the question above, we have

distance = 10km

time = 15 min = 0.25hr 

So the speed at which his father has to drive can be obtained by simple speed formula,

speed = distance/ time

speed = 10 km /0.25 hr

speed = 40km/hr