A sociologist records the annual household income (in thousands of dollars) among a sample of families living in a high-crime neighborhood. Locate the lower, median, and upper quartiles for the times listed below. Hint: First arrange the data in numerical order. lower quartile ____ thousand dollarsmedian ______ thousand dollars upper quartile ______ thousand dollars33 55 39 44 34 48 25 39 23 45

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Answer:

The lower quartile is [tex]Q_1=33[/tex] thousand dollars.

The median quartile is [tex]Q_2=39[/tex] thousand dollars.

The upper quartile is [tex]Q_3=45[/tex] thousand dollars.

Step-by-step explanation:

The lower quartile is the median value of the lower half of a data set at the 25th percentile of a distribution.

The median quartile is the median value of a data set at the 50th percentile of a distribution.

The upper quartile is the median value of the upper half of a data set at the 75th percentile of a distribution.

To locate each quartile in a data set, we follow four steps:

Step 1: Put the numbers in order: 23, 25, 33, 34, 39, 39, 44, 45, 48, 55

Step 2: The median is given by [tex]\frac{n+1}{2}[/tex] where n is all scores in the data set.  

Because n = 10, the median position is [tex]\frac{10+1}{2}=5.5[/tex]

The median is the average of the fifth and sixth positioned scores

[tex]Q_2=\frac{39+39}{2} =39[/tex]

Step 3:  Compute [tex]\frac{n+1}{2}[/tex] where n is all scores below [tex]Q_2[/tex].

For scores below [tex]Q_2[/tex], use only 23, 25, 33, 34, 39.

Because n = 5, the median position is [tex]\frac{5+1}{2}=3[/tex]

The median is the third positioned score: [tex]Q_1=33[/tex]

Step 4: Compute [tex]\frac{n+1}{2}[/tex] where n is all scores above [tex]Q_2[/tex].

For scores above [tex]Q_2[/tex], use only  39, 44, 45, 48, 55

Because n = 5, the median position is [tex]\frac{5+1}{2}=3[/tex]

The median is the third positioned score: [tex]Q_3=45[/tex]