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Answer:</h2>
The First Quartile is incorrect.
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Step-by-step explanation:</h2>
Step 1: Order the Numbers
They should looks like this: 12 12.2 12.3 12.6 12.8 12.8 13.5 13.9 14 14.2
Step 2: Find the Median
Since there is an even amount of numbers (10), the median is the sum of the two middle numbers divided by two: 12.8 + 12.8 = 25.6, 25.6 ÷ 2 = 12.8. So, 12.8 is our Median. Since our next steps will involve us figuring out more Medians, we will call this the "original Median." (I would suggest you replace the two numbers with one 12.8 and circle it so you know that this is the Median.)
Step 3: Find the Median for the Quartiles
Now you need to find the Median for the numbers leading up to the "original" Median and the numbers following the "original" Median. Since there is again, an even amount of numbers (4), you will add the two middle numbers of those four and divide the sum. Leading up to the Median: 12.2 + 12.3 = 24.5, 24.5 ÷ 2 = 12.25 (First Quartile). Following the Median: 13.9 + 14 = 27.9, 27.9 ÷ 2 = 13.95 (Second Quartile). (Again, I would suggest you replace each two numbers with the one median and circle it so that you will know that these will be the end of your first and third quartiles.)
Step 4: Find the Quartiles
Referring to Jack's Box Plot, the end of his line should start at 12 (that is the lowest number) and should end at 14.2 (that is the highest number). The "original Median" is 12.8, which will be the line inside of his box. Since we figured out what the median is leading up to the "original Median", his box should start at 12.25, and since we figured out the Median following the "original Median" we know that his box should end at 13.95.
Step 5: Make sure they match up
Let's organize this a bit better; numbers 12 - 12.25 (first quartile), 12.25 - 12.8 (second quartile), 12.8 - 13.95 (third quartile), 13.95 - 14.2 (fourth quartile). All of these match correctly except for our first quartile. It starts correctly at 12 but does not end at 12.25 and instead ends around 12.5.
Incorrect: First Quartile
After working out the problem and figuring out what Jack did wrong, we now know that Jack incorrectly worked the First Quartile.
<em>Hope this helped and that it wasn't too confusing. Also, if it was too confusing, try reading it and working out the problem yourself as you read the steps. :)</em>
