The given table shows the number of students in nine different classes. According to the table, what is the mean number of students? Round your answer to the nearest tenth.
We’re looking for the mean. To find the mean, we add up all the values and then divide by the number of values there were. In this case, we have nine classes. And so, we need to add up the number of students in all nine classes and then divide by nine. That would be 22 plus 25 plus 24 plus 26 plus 23 plus 24 plus 23 plus 23 plus 27. And then, I’d double-check that there were in fact nine values.
Now this process of writing down all nine values and then counting them could also be done on your calculator. You could type the nine values directly into your calculator. And whatever that’s equal to, we need to divide by nine. When we combine all nine of these values, we get 217. And we need to divide 217 by nine. When we do that, we get 24.1 repeating. Since we’re trying to round to the tenth place, we consider the digit to the right of the tenths place which is a one. And that means we’ll round down. We’ll round 24.1 repeating to 24.1. Let’s look at one more way to solve this problem.
In our list, we notice that all of the classes have twenty-something students. So what we can then do is write how many more than 20 each class has. So class one has two more than 20. Class two has five more than 20. Class three has four. Class four has six. Class five has three. Class six has four. Class seven has three. Class eight has three. And class nine has seven. If we add up all nine of these values, it comes to 37. And if we divide this total by nine, we get 4.1 repeating. Well, every class has 20 and the average of the more than 20 is 4.1 repeating. And so, we combine these two values to get 24.1 repeating, which when rounded to the nearest tenth becomes 24.1.