2.2.3 Grouped frequency distribution tables

In this activity, you will produce a grouped frequency table in Excel by following the instructions given below. Once you have produced the grouped frequency table in Excel, you can check your answer by clicking ‘Reveal discussion’.

• Open the Excel file JC Electrics template.
• Open the worksheet named ‘Grouped frequency table’. This is the third worksheet in the file JC Electrics template.
• In Column A you already have the data for Generators sorted.
• The tables for the following column are indicated as: Column B: Class intervals; Column C: Lower limit of class intervals, Column D: Upper limit of class intervals, Column E: Frequency and last column,
• Calculate the range. As mentioned before, this is the difference between the maximum and minimum value in the data set. For Generators, you can do this either by entering the formula =MAX (A5:A28)-MIN (A5:A28), or by calculating this on a separate section in the spreadsheet. For example, insert the formula =MAX(A5:A28) in cell J4. Insert formula =MIN(A5:A28) in cell J5. Calculate the rage in cell J6 by inserting the formula =J4-J5.

• Decide the class interval width. There are no firm rules on how to choose the width. However, the following formula is the most common method to calculate the width:

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• You can round this value to a whole number or a number that is convenient to add (such as multiple of 10). For example, the width calculated in the given data set is 1.63, so will be taken as 2 (see Figure 12). The =SQRT(number) is the formula in Excel for calculating a square root.

• Decide the number of groups or class intervals into which data is to be distributed. Each class interval is defined by a lower limit and an upper limit. The lower limit of first class interval is the lowest value in the data set, in our case 7. Add the class interval width to find the lower limit of the next class interval. Keep adding the interval width to calculate more class intervals until you exceed the highest value. For example, in the given data set, you determined the class intervals width equals 2, so you should make the class intervals as 7_8, 9_10, 11_12, 13_14, 15_16.
• This means that the first class interval has lower limit of 7 and upper limit of 8. See Figure 13 below.

• Next step is to calculate the frequency. This will be displayed in the section E5:E9. In cell E5 insert the formula =FREQUENCY(A5:A28,D5:D9). This will return the values 6 in the first cell followed by 7, 6, 4, 1 and 0.
• As you see, the Upper limit of class interval is selected here, therefore the returned value 6 indicates, that 6 times up to 8 units of Generators were sold. The next calculation in cell E6 shows a value of 7, therefore there 7 times Generators were sold with up to 10 units, but above 8 and so on.
• Check your answers in the Excel file: JC Electrics (solved).
• Optional: As further practice, you can now use the data for the other two products from JC Electrics 1 (Electric motors and Transformers) to identify the class intervals, lower limit of class interval, upper limit of class interval and frequency.
• You can check your answers in for solved files: JC Electrics (solved) Electric motors and JC Electrics (solved) Transformers.