Question

A car travels 30km at a uniform speed of 40km/h and the next 30km at a uniform speed of 20km/h. find its average speed

Answer 1

t1=distance÷speed
=30/40
=3/4
t2=distance÷speed
=30/20
=3/2
total time=3/4+3/2
=9/4
avg speed=total distance÷total time
=60÷9/4
=60×4/9
=26.6