A particular beach is eroding at a rate of 4 centimeters per year. A realtor converts this rate to millimeters per day. Which expression, when evaluated, results in the correct units and numerical value?

So the beach is eroding at a rate of 4 centimetres per year ...

Firstly, let's think about what a centimetre is ...

A centimetre is actually equal to 10 millimetres. This would mean that 4 centimetres is equal to 40 millimetres.

Let's change the sentence we started off with to:

"A particular beach is eroding at a rate of 40 millimetres per year."

Now we know that there are 365 days in a year, so we can transform the sentence just above into:

"A particular beach is eroding at a rate of 40 millimetres per 365 days."

From here we can tackle the problem and come up with a solution ...

Let's divide 40 by 365 to find out how much the beach is eroding every day.

40/365 is equal to 0.11 (to 2 decimal places)

This means that the beach is eroding at a rate of roughly 0.11 millimetres per day.