[Video] Q38: The mean of the scores for group a is 5, and the mean of the scores for group b is 7. what is the mean of the scores for the 20 players in groups a and b combined?

Explanation for Question 38 From the Math (Calc) Section on the 2019 October Sat

Now question number 38, we're told that the mean score of group a is 2 five and the mean score of group B is seven. 3 And then we need to know what is the mean score for all 20 4 players in both groups. And so for this problem, 5 we need to know what, how to solve for the mean, 6 right? And we know that the mean is all numbers added together. 7 So all of our values added divided by the number of 8 values. In this case, 9 we see that we have 20 players. 10 So that means that we would have 20 values to add together. 11 So we're going to be dividing by 20. And now the question is how 12 do we find our numerator? And so you should be able to actually add 13 all these values together, right? Add two ones, 14 um, or one to one, 15 three to fours, add all those together, 16 but the faster way, and the reason that they gave you this information right 17 here is to use the mean, 18 so let's dive into what the mean of a is, 19 right? 20 Because if we're finding the mean a value, then that means it's the sum 21 of all the A's divided by the number of A's. 22 And this is really what we're interested in here is the sum of the 23 A's, right? Because we need to sum all the A's and some, 24 all the BS together to get our numerator here. 25 And so if I know that the mean of AA is five, 26 and we know that there are nine individuals and a, 27 then it would have been something divided by nine, 28 right? So I can multiply both sides of this by nine to see 29 that 45 would be the sum of all my va...