Step by step
The question
Question: draw a box plot of 5, 8, 6, 9, 7, 10 and 4.
A box plot shows how the numbers spread out.
The box holds the middle half.
1 Put them in order
First we put them in order, smallest first: 4, 5, 6, 7, 8, 9 and 10.
2 Find the median
7 numbers: 3 on each side of the middle one.
The median is 7.
3 Find Q1 and Q3
The median cuts the list in two halves, 3 numbers each.
The median itself is in neither half.
Careful!
The median is not counted in the halves.
Each half has 3 numbers.
Q1 is the middle of the lower half: 5.
Q3 is the middle of the upper half: 9.
4 Five-number summary
The five-number summary: the smallest 4, Q1 5, the median 7, Q3 9, and the biggest 10.
5 Draw the box plot
A number line from 4 to 10.
The box goes from Q1, 5, to Q3, 9.
A line across the box at the median, 7.
The whiskers reach out to the smallest, 4, and the biggest, 10.
6 Check
Let's check: the median has 3 numbers below it and 3 above it.
Each half of the plot holds the same count.
So it is right!
Let's look back.
First: put them in order.
Then: find the median.
Then: find Q1 and Q3.
Then: five-number summary.
Then: draw the box plot.
Last: check.