SAT Math Multiple Choice Question 523: Answer and Explanation
13. If the values in the table represent a linear relationship, what is the missing value?
- A. 21
- B. 30
- C. 35
- D. 42
Correct Answer: C
Category: Heart of Algebra / Linear Equations
Strategic Advice: The rate of change (or slope) of a linear relationship is constant, so find the rate and apply it to the missing value. You could also look for a pattern in the table.
Getting to the Answer: Choose any two points (preferably ones with the nicest numbers) from the table, and substitute them into the slope formula. Using the points (3, 0) and (–1, 14), the slope is This means that for every 2 units the x-value decreases, the y-value increases by 7, and the decrease from x = –5 to x = –7 happens to be –2. So, increase the y-value by 7 one time: 28 + 7 = 35.