PSAT Math Multiple-Choice Question 424: Answer and Explanation

Question: 424

A teacher is buying supplies for the upcoming school year. Every year, basic classroom supplies such as chalk and paper cost her $500, and she spends an additional $25 per child in her class. The school reimburses her $10 per child for half the children in her class. Which function best describes the amount, in dollars, that the teacher spends per school year on supplies, given that s represents the number of students in the class?

• A.
• B.
• C.
• D.

Correct Answer: A

Explanation:

A

Difficulty: Medium

Getting to the Answer: The teacher spends $500 plus $25 per child, or 500 + 25s. But she is reimbursed $10 for half of the children in the class, so subtract 10(0.5)(s) to give 500 + 25s - 5s = 500 + 20s. The correct function is f(s) = 500 + 20s, which matches (A).