Step by step
The question
Question: draw a histogram of 0, 4, 9, 3, 7, 1, 5, 8, 2, 6, 4, 5 and 3, in classes of 2.
Which class has the most?
1 Make the classes
The smallest number is 0 and the biggest is 9.
In classes of 2: 0 to 1, 2 to 3, 4 to 5, 6 to 7 and 8 to 9.
2 Make a frequency table
A frequency table first: one row for each class.
0 is in 0 to 1: a mark there, and we cross out 0.
4 is in 4 to 5.
And so on for every number.
We count the marks: 2, 3, 4, 2 and 2.
3 Draw the bars
Along the bottom: the numbers, from 0 to 10.
Up the side: how many.
0 to 1: 2 numbers.
The bar covers 0 to 2 and goes up to 2.
2 to 3: 3.
4 to 5: 4.
Careful!
The bars touch.
The numbers go on with no gaps, like a number line.
A bar chart has gaps; a histogram does not.
4 Read the histogram
The tallest bar is 4 to 5.
It reaches 4.
So the class with the most is 4-5, with 4 numbers.
5 Check
Let's check: all the bars together are 2 plus 3 plus 4 plus 2 plus 2, which is 13.
That is every number in the list.
So it is right!
Let's look back.
First: make the classes.
Then: make a frequency table.
Then: draw the bars.
Then: read the histogram.
Last: check.