Explanation for Question 37 From the Math (Calc) Section on the Official Sat Practice Test 8
So for question 37, we're going to refer to this table in this graph 2 here in question 37, asks us according to the table. 3 So it's told us where to look. We're looking at the table, 4 not the graph, how many more micrograms of penicillin are present in 10 5 milliliters of blood, five minutes after injection versus eight milliliters 6 of blood, 10 minutes after injection. So basically we have two scenarios, 7 right? We have scenario a, which is 10 milliliters, 8 five minutes after. And we have scenario B, 9 which tells us eight milliliters, 10 minutes after. 10 Now, if we look up here at the table, we can see that we 11 have the five and we have the 10. And so you might be tempted 12 to just do 1 52 minus 18. 13 However, that will not give us the correct answer, 14 because this is in micrograms per milliliter. 15 So these are both for one milliliter, 16 and we know that we need to convert them to different amounts of milliliters, 17 right? 18 So let's start with the five. If five minutes we have 152 micrograms 19 per milliliter, but if I want 10 milliliters, 20 then I need to multiply by 10. So for situation a, 21 I would actually have one, five to zero micrograms because I have 10 milliliters 22 of blood rather than one milliliter. 23 And now for 10 we have 118 micrograms per milliliter. 24 So 118 micrograms per milliliter. 25 And we can see that I actually want eight milliliters of blood rather than 26 one. So I need to multiply by eight milliliters. 27 And when I do one 18 times eight, I get 944. 28 So now this is a taken into account. 29 The milliliter amounts that we were asked for, 30 and I can find the difference between these two numbers. 31 And when I subtract 944 from one five to zero, 32 I get 576, which is going to be our answer.