You have $10.00 to spend on a birthday gift. So you go to the dollar store where each item costs exactly $1.25. You also have to pay $1.25 no matter how many items that you purchase. Let the number of items be represented by the variable n. What is the cost function?

Question

a.
cost = $1.25 x n

b.
cost = $1.25 x n + $1.25

c.
cost = $10.00 - ($1.25 x n + $1.25)

d.
cost = $10.00 + ($1.25 x n + $1.25)

Answer 1

To determine the correct cost function based on the information provided, let's break down the components:

1. Each item costs $1.25.
2. There is a flat fee of $1.25 that is incurred no matter how many items you buy.
3. We want to express the total cost as a function of the number of items \( n \).

The total cost would consist of the cost of the items plus the flat fee:

• The cost for \( n \) items is \( 1.25n \).
• The flat fee is another \( 1.25 \).

So the total cost function can be written as:

\[ \text{cost} = 1.25n + 1.25 \]

This corresponds to option b:

b. cost = $1.25 x n + $1.25