Explanation for Question 7 From the Math (Calc) Section on the 2018 March Sat
Question seven says a website administrator is considering using one of the two 2 models above to predict the total number of purchases he made X 3 weeks after the websites, advertising campaign begins. 4 How many more purchases are predicted by the exponential model than by the linear 5 model five weeks after the advertising campaign begins. 6 So let's start by plugging in five to the exponential model, 7 which is this bottom one. So 500 times two to 8 the five that's equal to 500 times 32, 9 which is 16,000. 10 Now we can plug five into the top equation, 11 the linear equation to get 2000 times five, 12 which is equal to 10,000, 13 then only have to do is take 16,000 and subtract 10,000. 14 And that gives us 6,000 for answer choice.