Explanation for Question 28 From the Math (Calc) Section on the 2019 April Sat
In 28, we want to find the line of best fit for the scatterplot. 2 So the first thing we can do is find the slope to eliminate some 3 answer choices. So I will pick this point here and this point 4 here. So now we can do rise over run 5 to find our slope. We have to pay attention to units of both axes. 6 So we can see the Y axis is increasing by units of 10 for 7 every square. So the rise is going to be 10 20, 30, 8 and then four run each Square's increasing by 20. 9 So now we have 20, 40, 60, 8101 20 10 and one 40. So using a calculator 30 11 over one 40 rounds to about 0.21. 12 So now we know that that is our slope and we can get rid 13 of B and D. 14 So now what we need to look at is the Y intercept. 15 We have 32 or 62. 16 If we look at our graph here, it does seem to cross at 62. 17 However, it doesn't happen at a height of zero feet. 18 It happens at a height of one 40 feet. 19 So it's not going to be a Y intercept of 62, 20 that leaves 32. So you can go ahead and use process of elimination and 21 choose a, but if you want to double check, 22 we can plug in our values. So we said it's about 62 23 equals 0.21 H plus 24 the Y intercept that we're looking for. 25 I'll call it X. We know our H is one 40. 26 If we're plugging in that left-most point. 27 So I will plug in one 40 here. 28 Then if you do 0.2, one times one 40, 29 that is 29.4, 30 then 62 minus 29.4 is 31 equal to 32.6, 32 which is about 32. So a is the correct answer.