Question 315466
First order your data.
4,5,5,7,8,9,9,9,9,(12),
14,16,16,16,17,18,21,21,25
For the average, sum the numbers and divide by {{{19}}}.
Average={{{12.68}}}
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The median is the middle data once arranged in order.
Since you have an odd number of values, take the middle (the 10th) one.
Median={{{12}}}
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The mode is the value that occurs most.
Mode={{{9}}}
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The midrange is the avearge of the minimum and mazimum values.
Midrange={{{(4+25)/2=14.5}}}
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4,5,5,7,(8),9,9,9,9
The first quartile is the middle value of the first half. 
First quartile={{{8}}}
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14,16,16,16,(17),18,21,21,25
The third quartile is the middle value of the second half. 
Third quartile={{{17}}}