The third column is optional/extra. It's to show which data values fit in what specific class limit interval.
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Explanation:
Imagine we had a bunch of cards. Each card will have a number that is from the data set {70, 88, 103, 64, ... etc}
The goal is to sort the cards into 7 boxes. The first box is labeled "60 through 66", the next is "67 through 73", etc.
The first box has 4 cards placed inside it because we have the values {64,65,60,60 } which fit the interval from 60 through 66. Therefore the frequency here is 4.
The next box has the cards labeled {70,69,71,72,70 } inside it. We have 5 cards here, so the frequency is 5.
This pattern is kept up until all of the cards have been sorted into the proper boxes.
What you'll end up with is what you see in the image below. It shows the table of class limits with their corresponding frequencies. I have added a third column to show which values go where, which is optional and likely something you wont put as your answer to the teacher. This third column is just something for you to help keep track of everything.
