# SAT Math Multiple Choice Question 316: Answer and Explanation

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**Question: 316**

**1.** A biologist develops the equation y = 20.942x + 127 to predict the regrowth of a certain species of plant x months after a natural disaster occurred. Which of the following describes what the number 20.942 represents in this equation?

- A. The estimated number of the plants after x months
- B. The estimated monthly increase in the number of the plants
- C. The estimated monthly decrease in the number of the plants
- D. The estimated number of the plants that survived the natural disaster

**Correct Answer:** B

**Explanation:**

B

Difficulty: Easy

Category: Heart of Algebra / Linear Equations

Strategic Advice: Look at the structure of the equation. It is written in the form y = mx + b. In a real-world scenario, m is the rate of change and b is the initial amount.

Getting to the Answer: The question is asking about 20.942, which is m in the equation, and therefore represents a rate of change. The variable x represents number of months. The value of m is positive, so it represents the estimated monthly increase in the number of the plants after the natural disaster occurred.