Explanation for Question 13 From the Math (Calc) Section on the 2020 March Sat
So number 13 tells us about Natasha who can process ID card 2 applications. As we see here on the x-axis and also driver's license applications, 3 which we see on the why. And what we're looking for here is N 4 and what's important about N is that we need to know the N is 5 the minutes for driver's license. 6 So DL we'll call that plus the minutes for ID 7 cards, right? So it's both of the minutes combined. 8 And what's important to notice is that we have all of the possible combinations 9 of IDs and driver's licenses plotted on this graph right here. 10 Right? So in one case she could process 27 driver's 11 licenses and zero ID cards. 12 And if we know how many of each Natasha processes, 13 we can multiply the number of cards by the time it takes per each 14 card and then add them together so that we get an, 15 which is the total number of minutes. 16 And so perhaps what stumped you on this question was figuring out which point 17 to choose. But in reality, regardless of which of the points you choose on 18 this graph, you should still get the same number for N because it's a 19 linear function. So to show you that we'll test two points here, 20 right? We'll test this point and we'll test this point. 21 And I've chosen these two specifically because you'll notice that they both have a 22 zero involved, right? Um, 23 one of the types of cards would have a zero and that just simplifies 24 the math and can save you a few seconds. So if we look here, 25 right, there's one possib...