An inequality fits a sales goal that can be met or exceeded: at least includes the goal itself. Add the sales already made to the price times the number of new items, then use a Desmos regression on the equality to find the cutoff. Don’t stop at the dollars still needed when the question asks for a number of items.
Hints
- Hint 1
Let be the number of additional cookies. Each new cookie adds in sales, so new sales are . How would you combine that with the amount the bakery has already made?
- Hint 2
The boundary is where sales exactly reach the goal. Find that value by changing the inequality to an equality. Since at least includes equality, would the bakery need one more cookie if the boundary is a whole number?
Step-by-step
Model the goal and find the cutoff
Step 1Turn the sales goal into an inequality
Let count additional cookies. They bring in in new sales, which you add to the already made. The total must be at least , so . The symbol means “greater than or equal to.” Don’t multiply the by ; those sales have already happened.
- Step 2
Find the boundary and choose the minimum
To find where sales exactly reach , type in Desmos. The subscript in makes it a value Desmos can find, and asks Desmos to fit the equality. Under PARAMETERS, it shows . An exact whole-number boundary counts when the goal says “at least.” So the bakery must sell 8 additional cookies. Choice D.