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?

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

Step-by-step explanation:

Velocity formula:

Velocity is distance divided by time, that is:

Shortest route:

400 miles in 10 hours, which means that . So

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:

Then

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.