Question

The shortest route from London to Edinburgh is 400 miles.

A lorry is expected to take 10 hours to travel this route.
The lorry actually travels by a different route which increases the distance by 15%, but it still arrives in 10 hours.
By how many more mph than the expected speed does the lorry travel?

Answer 1

The lorry travels by 6 mph more than the expected speed.

Explanation:

Velocity formula:

Velocity is distance divided by time, that is:

`v = (d)/(t)`

Shortest route:

400 miles in 10 hours, which means that
`d = 400, v = 10`. So

`v = (d)/(t) = (400)/(10) = 40`

In mph.

The lorry actually travels by a different route which increases the distance by 15%, but it still arrives in 10 hours.

Distance is multiplied by 100% + 15% = 115% = 1.15, so:

`d = 1.15*400 = 460`

Then

`v = (d)/(t) = (460)/(10) = 46`

46 mph

By how many more mph than the expected speed does the lorry travel?

46 - 40 = 6 mph

The lorry travels by 6 mph more than the expected speed.