Question

a car cover 30 km at uniform speed of 40 km per hr and the next 30 km at uniform speed of 20 km per h find average speed

Answer 1

Speed=40km/h
distance=30km
time=d/s
       =30/40=0.75h
speed=20km/h
distance=30km
time=30/20
       =1.5h
total distance=30+30=60km
total time=0.75+1.5=2.25h
average speed=total distance/total time
                        =60/2.25=26.67km/h