Question

Anil completes the 72km journey between Bristol and Cardiff in 48 minutes.

He then drives 69km from Cardiff to Swansea at an average speed of 60km/h
Work out Anil's average speed(in km/h) for his total journey from Bristol to Swansea.

Answer 1

total distance travelled=72+69=141

time taken in hours for journey= (48/60)h + (69/60)= 1.95 h

average speed=141km/1.95h= 72.3km/h (3 sf)

Answer 2

think about the journey as two parts and the total journey.

first part:

first you need to find the speed of the first part but you need to convert 48mins to hours which is 0.8 hours.

speed = 72 ÷ 0.8 = 90km/h.

second part:

then you need to find the time it took to complete the second part of the journey.

time = distance/speed = 69 ÷ 60 = 1.15hours

total:

then you can find the total distance for both parts of the journey by doing 72km + 69km which is 141km.

the total time would be 0.8 hours + 1.15 hours which is 1.95 hours.

now you have the total distance and time so you can find the average speed for the whole journey.

speed = distance ÷ time

= 141 ÷ 1.95

= 72.307692307.... km/h

(you can round your answer to 72.3km/h)