Statistics from grouped data

Statistics from grouped data

Measures of centre from grouped data

• Mean can be estimated without knowing every individual data value

• First find class centre or midpoint of each grouped class interval

• Then use the frequencies to find the mean

Fill in the Blank

The class centre for a class interval of 20-24 is ___

Multiple Choice

A manufacturer has orders from 50 different retailers for a particular product each week. The order numbers are in the picture. Select a suitable class interval first

• 20

• 50

• 80

Fill in the Blank

A frequency table is constructed. Refer to the table, use your calculator and find out the mean number of orders. Correct to the nearest whole number.

Multiple Choice

The median class interval is ___, the modal class interval is___.

• 250-299, 250-299

• 250-299, 300-349

• 300-349, 250-299

• 300-349, 300-349