The number of public school teacher strikes in Pennsylvania for a random sample of school years is shown.

9

10

14

7

8

3

We will now  find the sample variance and sample standard deviation.

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Step 1: Find the mean of the data values

\[\bar{X}=\frac{\sum X}{n}=\frac{9+10+14+7+8+3}{6}=\frac{51}{6}=8.5\]

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Step 2: Find the deviation for each data value \((X-\bar{X})\)

9-8.5=0.5	10-8.5=1.5	14-8.5=5.5
7-8.5=-1.5	8-8.5=-0.5	3-8.5=-5.5

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Step 3: Square each of the deviations \((X-\bar{X})^2\)

\((0.5)^2=0.25\)	\((1.5)^2=2.25\)	\((5.5)^2=30.25\)
\((-1.5)^2\)	\((-0.5)^2=0.25\)	\((-5.5)^2=30.25\)

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Step 4: Find the sum of the squares

\[\sum (X-\bar{X})^2=0.25+2.25+30.25+2.25+0.25+30.25=65.5\]

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Step 5: Divide by \(n-1\) to get the variance

\[s^2=\frac{\sum (X-\bar{X})^2}{(n-1)}=\frac{65.5}{6-1}=\frac{65.5}{5}=13.1\]

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Step 6: Take the square root to get the standard deviation

\[s=\sqrt{\frac{\sum (X-\bar{X})^2}{(n-1)}}=\sqrt{13.1}\approx 3.6 \text{ (rounded)}\]