Explanation for Question 38 From the Math (Calc) Section on the 2020 March Sat
Now number 38 asks us what is the number of computers for which the 2 line of best fit predicts a value less than the actual value. 3 So here in this graph, right, our line of best fit I have now 4 outlined here in purple. And then each of our actual data points from actual 5 computers are the little circles here that we can see. 6 So these are our actual values, 7 right? And what we essentially need to see is where the line 8 was lower than the actual value. 9 So all of these points that are above the line are what we're looking 10 at, and we just need to count how many they are, 11 how many are there, right? Because each of these points is one computer. 12 So if I have 1, 2, 3, 4, 5, 6, 7, 8, 9, 13 if I have nine points where the line underestimated, 14 that means that there were nine computers where the actual price was higher than 15 that, of the line of best fit. So the key for this question is 16 knowing that each point represents a computer and that the points are the actual 17 values. So points are the actual, 18 and that's what we're comparing to the line. And that shows us that nine, 19 um, computers, um, where there were nine computers where the actual value 20 was in fact higher than the line of best fit.
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