PSAT Math Multiple-Choice Question 800: Answer and Explanation

Question: 800

A refrigerant manufacturer recorded the pressure associated with certain temperatures in a refrigerator using its new refrigerant, ABC. Which equation best approximates the best-fit line portrayed by the data in this graph, using P for pressure, T for temperature, and the same units as portrayed in the graph?

• A. P = 0.5T + 6.2
• B. P = T + 6.2
• C. P = 0.5T - 3
• D. P = 7T + 5

Correct Answer: A

Explanation:

(A) The y-intercept of the function is somewhere between positive 6 and 8, so we can eliminate choices (C) and (D). Next, find the slope. You can use any 2 points on the line of best fit, such as the endpoints:

So the answer is choice (A). The line has a slope of 0.5 and a y-intercept of 6.2.