PSAT Math Multiple-Choice Question 536: Answer and Explanation

Question: 536

A scientist at a greenhouse studied the relationship between the growth rate of a particular tree species and its current height. The conditions in the greenhouse were kept constant throughout the study period. The results are shown below, along with the graph of the exponential function that best models the data.

According to the model, which of the following is the best estimate of the plant’s growth rate, in millimeters per day, when the plant was 11 meters tall?

• A. 14
• B. 15
• C. 30
• D. 36

Correct Answer: D

Explanation:

D

The question asks for a certain value on a graph. Height is listed along the horizontal axis, so find 11 on that axis. It will be between the lines for 8 and 12, closer to the 12. From this point, trace up to find the intersection with the line of best fit, using the answer sheet as a straight edge if necessary. It is between the horizontal gridlines for 30 and 40 on the vertical Growth rate axis. Only the value in (D) falls between 30 and 40. The correct answer is (D).