SOLUTION: Find the first and third quartiles and the interquartile range for this sample. 730 670 610 520 690 650 600 570

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Question 358869: Find the first and third quartiles and the interquartile range for this sample. 730 670 610 520 690 650 600 570
Answer by neatmath(302) (Show Source):
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Arrange the sample numbers in order:

520 570 600 610 650 670 690 730

The median is 630 which is found by

The median is also the 50th percentile.

The first quartile (or lower quartile or 25th percentile) is the median of the bottom half of the numbers. Since there are 8 numbers, the bottom half is the first 4 numbers.

The median of the first 4 numbers is 585 which is found by

The third quartile (or upper quartile or 75th percentile) is the median of the top half of the numbers. Since there are 8 numbers, the top half is the last 4 numbers.

The median of the last 4 numbers is 680 which is found by

The interquartile range is simply the third quartile minus the first quartile.

or

First quartile is 585

Third quartile is 680

Interquartile range is 95

I hope this helps!