Explanation for Question 3 From the Math (Calc) Section on the 2020 March Sat
So for this next question, question number three, 2 we're asked to find what fraction of the marsupial species Australia marsupial 3 species are from this order para Mela morphia. 4 Right? And the first thing to notice is the, 5 of whenever you are trying to find a probability or a fraction, 6 and they've given you a table, keep your eye out for of, 7 because of, is going to tell you what is in your denominator. 8 You might be tempted to just get the total number of species overall, 9 add the 93 plus six plus one plus 71, 24, 10 et cetera, and add those together to get your denominator, 11 which might be why you were interested in choosing C or D because the 12 denominator was the total of all the species added together. 13 But in fact, that's not what we want here. And the reason that we 14 know that's not what we want is because the question tells us what fraction 15 of the Australian marsupial species. 16 So when we say of Australian marsupial species, 17 that tells us that only this part of our table, 18 the Australian section should be going in our denominator. 19 And if we add all of these numbers together, 20 all of our Australian species, we will get to 35, 21 right? So that's why C and D are going to be wrong. It's because 22 you looked at the total number of species rather than just the Australian. 23 Now for your look, uh, later on in our question, 24 it says which, um, what fraction of the S of the species are from 25 the order Paramellow morphea. And so if we jus...