The range of each group of data.
Example: you measure the length of leaves on a rose bush. Some are less than 1 cm, and the longest is 9 cm. You then put the lengths into groups.
A class interval of 2 cm has these groups:
• 0 cm to just below 2 cm,
• 2 cm to just below 4 cm,
• 4 cm to just below 6 cm,
• 6 cm to just below 8 cm,
• 8 cm to 10 cm.
But a class interval of 5 cm has these groups:
• 0 cm to just below 5 cm,
• 5 cm to 10 cm.