Question

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?

Answer 1

rate is 4cm/year = 40mm/365days ≈ 0.1096 mm/day

Answer 2

`(4cm)/(year) *(10mm)/(1cm) *(1year)/(365 days) =0.1096 mm/day`

Explanation:

There are ten millimetres in a centimetre. Therefore, the first step would be to multiply the centimetres by 10. First convert it to m/year:

`(4cm)/(year) *(10mm)/(1cm) =(40mm)/(year)`

Then to find the final answer in mm/day, the value of mm/year should be divided by 365.

`(40mm)/(year) *(1 year)/(365 days) = 0.1096 mm/day\\`

If you were to do this all in one step:

`(4cm)/(year) *(10mm)/(1cm) *(1year)/(365 days) =0.1096 mm/day`