Question

A bus travelling the first one third distance at a speed of 10 km per hour the next one third at 20 km per hour and the last one third at 60 km. Calculate the average speed of bus

Answer 1

Hi !

Let the distance traveled be "x" metres

x/3 metres is traveled at 10 km/hr speed ,
time = distance x speed
        = x/3 * 10
        = x/30

similarly ,
x/3*20 = x/60 

x/3*60 = x/180 

total time = x/30 + x/60 + x/180
               = 6x /180 + 3x/180 + x/180
              = 10x/180
              = x/18 

Average speed = total distance/total time
                         = x/(x/18)
                         = 18 km/hr