Question

A car travels at a speed of 80 km/h during the first half of its running time and at 40 km/ h during the other half. Find the average speed of the car. (60 km/h)

Answer 1

Let the car be travelled 1 hr in each half
In First half,
speed = 80 km / hr
time travelled = 1 hr
Therefore,
distance = 80 x 1
= 80 km

In second half,
speed = 40 km / hr
time travelled = 1 hr
Therefore,
distance = 40 x 1
= 40 km

Average speed = total distance / total time
Total distance = 80 + 40
= 120 km
Total time = 1 + 1
= 2 hrs
Therefore,
Average speed = 120 / 2
= 60 km / hr