Explanation for Question 4 From the Math (Calc) Section on the Official Sat Practice Test 6
Question four reads a website, hosting service charges businesses, 2 a one-time setup fee of 350 plus D dollars for each month. 3 If a business owner paid $1,010 for the first 12 months, 4 including the setup fee, what is the value of D? 5 So let's set up an expression that essentially translates these words into 6 an equation let's set Y equal to the total cost. 7 So we've got Y equals $350, 8 and we know that that's going to be a flat rate fee that we 9 just add on as a onetime, as a one-time attribute within the total cost, 10 because that's just this one-time setup fee. 11 And then we need to know how much are going to be charged per 12 month. So you know, that the D is a variable defining the dollars for 13 each month. So we have D times the 14 number of months. So number of months, 15 okay. So looking at this expression, 16 you can see that we have 1, 2, 3 unknowns. 17 So obviously we can't sell from there, but the key to solving this is 18 going to be in the second part of the question where it says if 19 a business owner paid $1,010 for the first 12 months. 20 Okay. So let's try and plug in that point. So in this instance, 21 our total cost is going to be $1,010, 22 and then let's write the rest of it. Three $50 plus D 23 times 12 months. 24 Okay. So now we have only one unknown. 25 We've got one equation, one unknown. So we can solve from here now, 26 going ahead and solving. We now have 1010 minus three 50, 27 it's going to be equal to six 60, and then we have 12 28 D. So to get D on its own, 29 we need to divide both sides by 12, which leads us with D is 30 equal to 55. And the units on D are going to be dollars 31 per month. So that's the monthly fee that is charged, 32 um, in association with the web hosting service and using it every month. 33 So with that, we know the value of date and we can circle D 34 as our answer choice.