Question

A lorry travelled 84km between two towns.the first 60km of the road was untarred and the average speed over this part was 30km/h.If the average speed for the whole journey was 36km/h.Calculate the average speed over the good part of the road

Answer 1

Answer:

Step-by-step explanation:

1/3 distance = 20 km. in 20 min. ( 60 km / 60 min)

2/3 distance = 40 km in 80 min. ( 30 km / 60 min)

Whole distance (1/3 + 2/3) = 60 km in 100 min

So average speed 36 km / 60 min ( 1 hr)

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