Question

4. BAKE SALE Ashley has $15 in the Pep

Club treasury to pay for supplies for a


chocolate chip cookie bake sale. The


function d = 15 - 0.08c represents the


dollars d left in the club treasury after


making c cookies. Find the zero and


describe its meaning in the context of the


situation? Identify the domain and range


and explain their significance.

Answer 1

a) 187.5 b) Domain c ∈ [0,187.5] c) Range ∈ [0,15]

Explanation:

a) In this function, d stands for dollars and c stands for cookies. Ashley left $15 to pay supplies for making new cookies. The more cookies they made the less money it is left. For instance, If someone bakes 1 cookie using that money:

d=15-0.08c d=15-0.08(1) d=14.92 Then $14.92 is left after baking 1 cookie. And so on.

To find the zero of this function, let's turn this into an equation.

`d=15-0.08c\\0=15-0.08c\\-15=-0.08c\\\ (0.08)/(0.08)c=(15)/(0.08)\\c=187.5`

So according to this function, with 15 dollars at least 187 cookies can be made.

b) The function d=15-0.08c if it was defined for the Real Set, any value would be valid within the Real Set. But c, is for cookies. Then the set is

`Z_(+)`

`d=15-0.08c\\0=15-0.08c\\-15=-0.08c\\\ (0.08)/(0.08)c=(15)/(0.08)\\c=187.5`

Domain c ∈ [0,187.5]

c) The Range

The Range is the subset of all values between $15 and 0$, since after the money is over they can no longer bake cookies. And there's $-1 dollar note.

So the Range is d ∈ [0,15]