Question

Dave ran 10km in 40 minutes. He rested for 5 minutes then ran a further 8 km in 35 minutes. Work out his average speed for the whole journey. (Give your answer in km/h)

Answer 1

His average speed for the whole Journey is 60 km/h

Explanation:

Mathematically;

Average speed is total distance/total time

taken

First part , 10 km in 40 minutes

40 minutes = 40/60 = 2/3 hours

Second part ; 8 km in 35 minutes

35 minutes = 35/60 = 7/12 hours

Total time = 2/3 + 7/12 = (8 + 7)/12 = 15/12 = 5/4 hours

Total distance = 10 + 8 = 18 km

Average speed = 18 km divided by 5/4 hours

5/4 hours = 1.25 hours

So average speed in km/h will be 75/1.25 = 60 km/h