Explanation for Question 9 From the Math (Calc) Section on the Official Sat Practice Test 1
So question nine has given us some information first off it's given us this 2 equation. And then it tells us that the speed of a Soundwave in air 3 depends on the temperature and the formula above. 4 So the one in orange shows that the relationship between a, 5 the speed of a sound wave and feet per second, and T in degrees 6 Fahrenheit. And we want to know which of the following expresses air temperature, 7 right? So we're trying to solve for T, which is right there. 8 And then in terms of the speed of the sound wave. 9 So in terms of a, and so that language might be unfamiliar, 10 right? You might not have heard in terms of, but that just means that 11 a is the variable that you're allowed to use in your equation, 12 which makes sense. Right? Because we see that each of our equations have the 13 variable a in them. 14 So basically we're solving for T and we're going to use the variable a 15 so we can start with our equation. A is equal to 1052 plus 1.08 16 T. And if I want to solve for T the first thing that I 17 need to do is get rid of anything that is being added or subtracted 18 to T and that's happening right here. 19 So I can start by subtracting that 1 0 5, 2 from 20 both sides. So that way it cancels here on the right, 21 it gets away from the T. And now I have a minus 1, 0 5, 2, 22 and that will be equal to 1.08 C. 23 And now I want to get rid of this 1.08, right? 24 Because my goal is to isolate T and that 1.08 is in the way. 25 So I can divide by 1.08 on both sides. 26 Now, this cancels, and I'll be left with a minus 1, 0 5, 2 over 1.08 27 is equal to T and now I've done it. I've solved for T I 28 have the variable a and my equation. We can see that this is the 29 same as answer choice. A so nine has to be a.