Question

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

Answer 1

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.