1. Grouped Data
L.O.
All pupils understand why grouped data is sometimes used
All pupils can find the modal class

2. Alternate methods of analyising the data have to be employed.
Grouped Data
Large quantities of data can be much more easily viewed and managed if placed in groups in a frequency table.
Grouped data does not enable exact values for the mean, median and mode to be calculated.
Alternate methods of analyising the data have to be employed.

3. Can you think of a time when grouped data would need to be used?

4. Grouped Data Example 1. 2 50 - 60 4 40 - 50 5 30 - 40 7 20 - 30 10
During 3 hours at Heathrow airport 55 aircraft arrived late. The number of minutes they were late is shown in the grouped frequency table below. 2 4 5 7 10 27
0 - 10
frequency
minutes late
Data is grouped into 6 class intervals of width 10.

5. The modal class is simply the class interval of highest frequency.
Example 1.
During 3 hours at Heathrow airport 55 aircraft arrived late. The number of minutes they were late is shown in the grouped frequency table below.
Grouped Data
The Modal Class 2 4 5 7 10 27
0 - 10
frequency
minutes late
The modal class is simply the class interval of highest frequency.
Modal class =

6. Grouped Data Example 2. Modal Class 26 - 30
A group of University students took part in a sponsored race. The number of laps completed is given in the table below. Use the information to determine the modal class. 1 2
31 – 35 25
26 – 30 17
21 – 25 20
16 – 20 15
11 – 15 9
6 – 10
1 - 5
frequency (x)
number of laps
Modal Class