Question

A man completes the few of journey by the motorcycle. in case he covered 30% of distance at speed of 20 kmph. 60% of distance at 40 kmph as well as remaining of distance at 10 kmph his average speed has been: ticka 25 kmph tickb 28 kmph tickc 30 kmph tickd 33 kmph

Answer 1

Let the total distance be x :

Distance travelled at 20 km/h is :

30/100 × x = 0.3x

Time = 0.3x/20

Distance travelled at 40 kmph

60/100 × x = 0.6x

Time = 0.6x/40

Distance at 10kmph:

10/100 × x = 0.1x

Time  = 0.1x/10

Average speed = Total distance / total time

Total time = x1/100 + 3x/200 + 6x/400 = (4x + 6x + 6x) / 400 = 16x/400 = x/25

Speed = distance / time

= x × 25 /x = 25 kmph