Question

The shortest route from London to Bristol is 120 miles.

A lorry is expected to take 2 hours to travel this route.
The lorry actually travels by a different route which increases the distance by 20%, but it still arrives in 2 hours.
By how many more mph than the expected speed does the lorry travel?

Answer 1

12 mph

Explanation:

First we're going to start by finding the difference in miles from the first route to the second route.

The first route is 120 miles and the second is 20% more than the first. To find the difference you should first multiply the 120 by 20%.

120*0.2=24

You then need to add the additional 24 miles to the original 120 to find the distance of the second route.

120+24=144

After we will begin to find the mph expected speed for both routes.

The first route was 120 miles and it was expected to take 2 hours to get there. This means you need to divide 120 by 2 to find out how many miles they were traveling within one hour.

120/2=60

So the expected mph for the first route would be 60.

We want to repeat the same thing for the second route.

144/2=72

The mph for the second route was 72.

Now you need to find out how much faster the mph was for the second route than the first by subtracting the first from the second.

72-60=12

The second route was 12 mph faster than the first.