The following stem-and-leaf plot represents the test scores for 26
students in a class on their most recent test. Use the data provided to find the quartiles.
Test Scores by Student
Stem Leaves
5
0
0
1
2
4
5
5
6
6
1
3
4
5
5
7
2
2
2
3
7
9
8
2
3
3
7
8
9
9
Key: 5|0=50
Step 2 of 3 : Find the first quartile.
To find the first quartile (Q1), we need to find the median of the lower half of the data.
The lower half of the data includes the first 13 scores:
0, 0, 1, 2, 4, 5, 5, 5, 6, 6, 6, 11, 13
Since there are 13 scores in the lower half, the median is the average of the 7th and 8th scores:
(5 + 5) / 2 = 5
So, the first quartile (Q1) is 5.