Digital PSAT Math Practice Question 19: Answer and Explanation

Question: 19

A marine biologist has conducted research into the population of blue whales over the past few decades. The estimated global blue whale population is plotted against the given year in the graph below:

From 1940 until 1970, the best-fit equation for the values of the blue whale population has which general characteristic?

• A. Linear decay
• B. Linear growth
• C. Exponential decay
• D. Exponential growth

Correct Answer: C

Explanation:

(C) Between 1940 and 1970, the blue whale population is decreasing and the function has a substantial curve. So the graph shows exponential decay. Note that if the decay were linear, the graph would have gone down in a straight line.