Question

Karis receives $90000 per year working as a manager. She spends 15% every 3 month on her daughters college tuition. Write a function rule for the amount of money that Karis still has as a function of time in month

Answer 1

`f(m) = 90000 - 0.05m`

Explanation:

Given

`Base\ Amount = \$90000`

`Spending = 15\%` -- every 3 months

Required

Determine the function that shows her monthly balance:

Represent month with m

If she spends 15% every 3 months;

Then

She spends 5% every month

i.e.

`monthly = (15\%)/(3)`

`monthly = 5\%`

If
`1\ month = 5\%`

Then

`m\ months = 5\% * m`

Monthly balance (f(m) is then calculated as:

`f(m) = Base\ Amount - Monthly\ Spending`

`f(m) = 90000 - 5\% * m`

`f(m) = 90000 - 0.05 * m`

`f(m) = 90000 - 0.05m`