Answer Choices
25,000 > 4,334 − 2,712 t
25,000 < 4,334 − 2,712 t
25,000 − 4,334 > 2,712 t
25,000 >4,332/2,712 t
Explanation for Question 20 From the Math (Calc) Section on the Official Sat Practice Test 8
So number 20 tells us that usually a homeowner spends about $4,000 2 on energy, but they're going to go ahead and they're going to spend $25,000 3 so that they can reduce their cost to just a little over half, 4 right. To about $3,000 every year. 5 As our question is when will the savings exceed the 6 installation costs? Right? First thing we can think about is what 7 is the installation cost? And the installation cost is $25,000, 8 right? So one of our sides of our equation should be $25,000. 9 That kind of tells us that C isn't going to work out because C 10 doesn't have the 25,000 on its own. 11 It has a subtracting this amount, which is not part of the installation cost. 12 And now we're looking for the savings. Now fall in a normal year, 13 we spend 4, 3, 3, 4, 14 but on this year, for example, 15 after we installed the energy saving, we're actually going to spend 2 71 16 to than the amount of energy that we save can be found by taking 17 the difference of that. 18 Right? So that's why we see this here. 19 And so we can really see that we want to take the difference. We 20 don't want to divide because we want to know how much money we're saving. 21 And we do that by finding the, the amount of money that is 22 the difference between these two, that's the money that we get to keep for 23 ourselves. And so if we're trying to decide between a and B, 24 we look at our question and we see that we want the savings to 25 exceed the cost right here only in B is the savings greater 26 than the cost actually. So shows the cost being greater than the savings. 27 So for that reason, our best answer is going to be B.