How do I make a box-and-whisker plot using 72, 73, 66, 71, 82, 85, 95, 85, 86, 89, 91, 92?

1 Answer
Mark D.
May 24, 2018

To draw a B&W plot you need 5 values
The lowest value
The highest value
The mean (#L_2#)
The lower quartile (LQ or #L_1)#
The upper quartile (UQ or #L_3#)

Put the numbers in order

66,71,72,73,82,85,85,86,89,91,92,95

The lowest and highest are 66 & 95 respectively

Mean: there are 12 numbers #=>(12+1)/2=6.5#

So the mean is between the #6^(th) & 7^(th)# numbers.

If the mean is between two numbers you add them together and half it. As the two numbers are 85 and 85 then the mean is 85

#L_1# is #(n+1)/4# which in this case is between the #3^(rd) & 4^(th)# numbers.
Between 72 & 73 is 72.5

#L_3# is #(3(n+1))/4# which in this case is between the #9^(th) & 10^(th)# numbers.
Between 89 & 91 is 90

So the 5 points to plot are

66, 72.5, 85, 90, 95

Sorry don't know how to draw it and display it on here.

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