[Video] Q13: Which of the following equations represents the relationship between the diameter, in inches, of a giant sequoia tree's trunk and that tree's age, in years?

Explanation for Question 13 From the Math (Calc) Section on the 2018 May Sat

Question 13 says which of the following equations represents the relationship between 2 the diameter in inches of a giant Sequoia tree trunk and that trees age 3 in years. So this question is asking us to find the equation of 4 this graph up here. And we're going to do that. 5 Using the Y equals MX plus B formula where M represents the slope and 6 B represents the Y intercept. The first thing we should note is that the 7 Y intercept is equal to zero, 8 which means that there should not be a constant in this equation. 9 And from that we can eliminate answer choices, 10 a and B next, 11 we can calculate the slope using any two points on the graph. 12 I'm just going to use zero, zero as our first point and 150 as 13 our second point, which tells me that the rise is 100 and the run 14 is 50, and that's just equal to two. 15 So our slope should be two. And our end value should be two, 16 which tells us that D is the correct answer.