Explanation for Question 33 From the Math (Calc) Section on the Official Sat Practice Test 10
Now for question number 33, 2 we're looking at this set of numbers that we have. 3 And we're told that the mean of the five numbers is 1600, 4 right? So we're talking about mean we have an equation, 5 I'll show you the fancy version. It looks like this, 6 right? So just, if you wanted to see the fancy version of the equation, 7 that's what it looks like, but we don't need to be using that particularly. 8 We can simply say that the mean is equal to the sum of all 9 of our numbers divided by the number of numbers. 10 Lovely. Okay. So all the numbers that we have are 700 1200, 1600, 200 11 and X, right? So we need to add all of those together and put 12 that in our numerator. So I'll do 700 plus 1200 plus 1600 13 plus 2000. And all of that is 5,500 plus X, 14 right? We can't forget about the X. 15 And the number of numbers that we have is 1, 2, 3, 4, 5. 16 It also tells us right here that we have five numbers. 17 And then we're told that the mean is 1600 right there. 18 He told us what the mean is. And so now we can use those 19 numbers to solve for X, right? 20 So I'll cross multiply here, multiply this side by five. 21 So we need to do five times 1600, 22 which is 8,000. We have 8,000 is equal to 5,500 23 plus X. And when I do 8,000 minus 5,500, 24 8,000 minus 5,500 in our calculator, 25 we get the X is equal to 2,500 making 26 our best answer. 2,500.