Question

A car travels first 30 km at a uniform speed of 20km/hr and next 30 km at a uniform speed of 40km/hr. what is the average speed?

Answer 1

Average speed = total distance travelled
                               total time taken

total distance = 30km + 30 km
                         =  60 km

time taken = distance
                       speed

Time taken 1= 30km/20km/hr
                       = 1 hr 30 mins

Time taken 2 = 30km/ 40km/hr
                       = 45 mins

total time = 1.5 + 0.75
               =    2.25hrs

               60km
           2.25hrs

           = 26.67 km/hr