SAT Math Multiple Choice Question 235: Answer and Explanation
The graph above represents the effect of efforts to reintroduce Chrysocyon brachyurus, a wolf-like predator, to Uruguay. It tracks the population of both Chrysocyon brachyurus and Sylvilagus brasiliensis, the rabbit species that is a primary food-source.
For which of the following periods did the Sylvilagus brasiliensis population undergo the greatest percent decrease?
- A. '91-'92
- B. '93-'95
- C. '99-'00
- D. '00-'01
Correct Answer: D
D To answer this question, you need the formula for percent change: · 100. For choice (A), plug in a difference of about 200,000 and an original of about 1,000,000: · 100. This simplifies to 20%. For (B), plug in a difference of about 200,000 and an original of about 900,000: · 100. This simplifies to about 22%, so you can eliminate (A). Choice (C) is incorrect because the Sylvilagus brasiliensis population increased during that time. If you chose (C), you may have calculated the percent change of the Chrysocyon brachyurus population. For (D), plug in a difference of about 200,000 and an original of about 800,000: · 100. This simplifies to approximately 31%. This is the greatest percent decrease; therefore, (D) is correct.