Explanation for Question 30 From the Math (Calc) Section on the 2020 October Sat
So for question 30, it'll first be useful to think about what are our 2 options as far as having siblings. 3 And so we know that students can have those siblings, 4 they could have two or more siblings, or they could have exactly one sibling. 5 And so now we can go back into the question and figure out what 6 numbers go, where, and we can assign a value to each of these categories. 7 Now we know that six students have no siblings, 8 so a six goes here and then we know that three times the number 9 of students and who have two or more siblings. 10 Um, so this actually gives us two numbers, right? 11 The number of students who have two or more siblings is N and three 12 times N have one. So this is three. 13 And now when I add all of these numbers together, 14 right, I should get the total number of students, 15 which is 30. And so when I add all these together, 16 I got six plus and plus three and is equal to 30, 17 but I can combine like terms and I get six plus four and is 18 equal to 30. And that leaves us the answer choice C.