Explanation for Question 12 From the Math (Calc) Section on the 2020 March Sat
Now number 12, we're looking at the distribution of students at a middle school 2 and the extracurricular activities that they participate in. 3 And in this question, we're told that the number of students who participate in 4 two extracurricular activities, 5 so that's going to be right here, 6 um, is 120 more. 7 So 120, more than the number of students who participate in one extracurricular 8 activity. And we need to know what is the total number. 9 So that's our final, our final question. 10 How many students go to this middle school? 11 And so we can use this information here in green to come up with 12 an equation that will allow us to find the total number of students and 13 that middle school. And we'll go ahead and we'll call that variable. 14 N so in other words, our question is what is N and how can 15 I create an equation that has N first thing we can do to create 16 this equation is notice that the number of students who participate in activities are 17 given as a percentage of the total, 18 right? 19 So 5% of all the students have no extracurricular activities. 20 So if I were to do 0.05 times N that would give me the 21 number of students who have no activities rather than the percentage. 22 So we can use that with this, um, 23 30% for the one in the 55% for the two, 24 this can be 0.3 times N 30% of the students. 25 Um, and the school have one extracurricular activity, 26 and this can be 0.55 N. 27 And those are going to be the two useful numbers for us. 28 And...