• A frequency table shows the values or classes together with the number of times each one occurs.
• It usually has three columns: the value (or class), tally marks, and the frequency.
• Tally marks are a quick way to count.
• Draw four vertical strokes and cross them with a fifth stroke, so that each group of five marks means 5.

Frequency table for classes

• When the values are many and spread out, we group them into classes of equal width.
• The class 140 – less than 150 includes every value from 140 up to, but not including, 150.
• The difference between the two limits of a class is called the class width.