# Frequency table

A frequency table helps us to organise and order data. We often use tally marks to help us construct frequency tables.

### Example

A teacher conducted a survey of shoe sizes of an S1 class. The results are shown below:

Shoe sizes of S1 class
$9, 8, 7, 8, 9, 9, 8$
$7, 5, 10, 8, 8, 6, 6$
$10, 5, 8, 6, 6, 10, 5$
$8, 9, 9, 10, 10, 8, 5$
$7, 6, 9, 8, 5, 4, 9$

These results are quite difficult to read. Organising the data in a frequency table helps show at a glance how many of each size there were.

### Making a frequency table for grouped data

Here is the data for the ages of customers in the Bitesize coffee shop.

Ages of customers in 1 hour period
$25, 29, 45, 19, 36, 17, 60, 51, 39, 24, 15, 13, 31, 18, 24, 32$
$37, 27, 23, 53, 41, 34, 29, 28, 52, 17, 55, 47, 34, 28, 22, 20$
$64, 39, 38, 33, 24, 16, 27, 19, 26, 27, 25, 32, 26, 48, 54, 35$

We could show this data in a table with one number in each row, but it would have a lot of rows!

We can group the ages together so that we have fewer categories.

This is the same set of data put into groups:

When choosing intervals for the data sets try not to make the intervals too big or too small.

You could use the above intervals to draw a frequency chart:

Question

Here is the data for the length of time (to the nearest minute) people took to fill in an application form.

Length of time (minutes)
$23,17,15,29,22,21,20,12,19,28$
$18,18,22,31,13,24,23,18,17,26$
$25,16,24,18,16,22,33,17,24,18$

Make a frequency table of this data.

(The answer below starts with 11-15, 16-20, etc. The interval choice is sometimes up to you)