Step by step
The question
Question: make a frequency table of 12, 15, 12, 13, 15, 15, 14, 12, 15 and 13.
The frequency of a number is how many times it comes.
1 List the values
We write each value once, smallest first: 12, 13, 14 and 15.
2 Tally
Careful!
Cross out each number as you count it.
Then none is missed, and none is counted twice.
The first number is 12.
We cross it out, and put one mark next to 12.
Next is 15: one mark next to 15.
And so on: one mark for each number.
Every number is crossed out.
So every number has its mark.
3 Count
12 has 3 marks: f = 3.
13 has 2 marks: f = 2.
14 has 1 mark: f = 1.
15 has 4 marks: f = 4.
4 Check
Let's check.
We add the f column: 3 + 2 + 1 + 4 = 10.
There are 10 numbers in the list.
Every one is counted.
So it is right!
Let's look back.
First: list the values.
Then: tally.
Then: count.
Last: check.