Q59 of 139 Page 22

A car travels 100 km at a speed of 90 km/h and returns with a speed of 30 km/h. Calculate the average speed for the whole journey.

In the first case, car travels at a speed of 90 km/h for a distance of 100 km


t1 = 100/90 h


In the second case, car travels at a speed of 30 km/h for a distance of 100 km


t2 = 100/30 h


Total distance travelled = 200 km


= 100/90 + 100/30



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