Question

One car moving on a straight road covers one third of the distance with 20 km/hr and the rest with 60 km/hr. The average speed is

Answer 1

Answer:

speed ( v ) = distance (s) / time (t)

let total distance is x km

case 1 ; when speed is 20 km/h

          20 = x / 3t

           t = x / 60 ------------(i)

case 2 ; when speed is 60 km/h

          60 = 2x / 3t

           t = x / 90 -----------(ii)

average speed = total distance / total time

                         = x / ( x/60 + x/90 )

                         = x ÷ 5x/180

                         = 180x / 5x

                         = 36 km/h

hope it helps !!!!!

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