Workout the average speed for the whole journey. Give your answer in km/h, correct to the nearest whole number

Question

Philip lives 10 km in 40 minutes. He rested 5 minutes then ran a futher 8 km in 35 minutes.

Answer 1

So, his distances of 10 km and 8 km total 18 km. Total time taken was 40 min + 5 min + 35 min = 80 minutes. In hours, 80 min = 1 hr 20 min or 1 20/60 or 1 1/3 hr.

1 1/3 hr. = 4/3 hr.

Average = total dist/ total time = 18 km/ (4/3)

÷ by 4/3 is same as multiplying by 3/4 the reciprocal.

18 x 4/3 = 72/3 = 24 km/ hr and no rounding is needed.