Question

A car travels 450km at 100km/h and 90km at 60km/h. Find its average speed?

Answer 1

Average speed = 90 km/h

Explanation:

Given that:

Distance covered at 100 km/h = 450 km

Time =
`(Distance)/(Speed)`

Time =
`(450)/(100)=4.5\ hours`

Distance covered at 60 km/h = 90 km

Time =
`(90)/(60)=1.5\ hours`

Total distance travelled = 450 + 90 = 540 km

Total time taken = 4.5 + 1.5 = 6 hours

Average speed =
`(Total\ distance)/(Total\ time)`

Average speed =
`(540)/(6)`

Average speed = 90 km/hr

Hence,

Average speed = 90 km/h