Algebra-1

To find Q3 (the third quartile) for the data set: 4, 7, 9, 11, 13, 16, 19, 21, 23, follow these steps:

Step 1: Order the Data Set
The data is already ordered:  
4, 7, 9, 11, 13, 16, 19, 21, 23

Step 2: Find the Median (Q2)
The median (Q2) is the middle value of the data set.
Since there are 9 data points, the median is the 5th value, which is:
Median (Q2) = 13

Step 3: Split the Data Set
- The lower half (left of the median): 4, 7, 9, 11
- The upper half (right of the median): 16, 19, 21, 23

Step 4: Find Q3 (the Median of the Upper Half)
Now, find the median of the upper half: 16, 19, 21, 23.
Since there are 4 values, the median will be the average of the two middle values, which are 19 and 21:

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