Explanation for Question 37 From the Math (Calc) Section on the 2019 March Sat
Question 37 says in a science classroom, 2 when labs are performed, students are seated at lab tables. 3 If the teacher assigns two students to each lab table for additional lab 4 tables, where we will be needed to see all of the students, 5 if this teacher assigns four students, 6 each lab table for lab tables will not be used. 7 How many students are in the science class. So to solve this equation or 8 to solve this problem, we're going to have to set up two equations and 9 we're going to have to use two variables. 10 We're going to use L which represents the number of lab tables and S 11 which represents the total number of students. 12 So the first equation, we're going to use this part here. 13 So if two students are at each lab, 14 table, four more lab tables will be needed. 15 So that means that two times the number of lab tables, 16 plus four times two. 17 So plus eight is equal to the total number of students. 18 Our second equation is going to use the second part from here to here. 19 So if four students are assigned to each lab table, 20 then for lab tables, won't be used. 21 So four times the total number of lab tables, 22 but minus four, lab tables is also equal to the tool, 23 to the total numbers of students. Then we can set these two equations equal 24 to each other. So two L plus eight is equal 25 to four L minus 16, 26 and I just distributed there. Then if I subtract two from both sides and 27 add 16, I get 24 is 28 equal to two L and that L is equal to 12. 29 So we know that there are 12 lab tables in the science class, 30 but we're looking for the total number of students, 31 which means that we need to take this value of L 12 and plug 32 it into one of our earlier equations. So let's take this top equation here 33 and let's plug it Ellen. So if we plugged 12 and for L we 34 get two times 12, which is 24 plus eight is equal to S 35 and we know that the answer and the total number of students is equal 36 to 30.