Question

A vehicle is moving from city a to city b with a speed of 40km/h and returns again to city a with a speed of 60km/h. calculate average speed

Answer 1

Let the distance between the cities be x

Average speed=Total distance/total time taken

total distance travelled is 2x

the total time taken is give by t1+t2 where t1 is the time taken to go from a to b and t2 is the time taken to go from b to a

s=vt

hence t1=s/v

=x/40

and t2=x/60

substituting we get average speed=2x/[(x/40)+(x/60)]

solving we get average speed=48km/h

Hope this helps