Statistics: Frequency Table ( In groups)

Class Intervals (or Groups)

When the set of data values are spread out, it is difficult to set up a frequency table for every data value as there will be too many rows in the table.  So we group the data into class intervals (or groups) to help us organise, interpret and analyse the data.

Ideally, we should have between five and ten rows in a frequency table.  Bear this in mind when deciding the size of the class interval (or group).

Each group starts at a data value that is a multiple of that group.  For example, if the size of the group is 5, then the groups should start at 5, 10, 15, 20 etc.  Likewise, if the size of the group is 10, then the groups should start at 10, 20, 30, 40 etc.

The frequency of a group (or class interval) is the number of data values that fall in the range specified by that group (or class interval).

Question: Where is frequency used in real life?

Statistics: Frequency Tables (Individual)

Frequency and Frequency Tables

The frequency of a particular data value is the number of times the data value occurs. For example, if four students have a score of 80 in mathematics, and then the score of 80 is said to have a frequency of 4.  The frequency of a data value is often represented by f. A frequency table is constructed by arranging collected data values in ascending order of magnitude with their corresponding frequencies. Example The marks awarded for an assignment set for a Year 8 class of 20 students were as follows:      6     7     5     7     7     8     7     6     9     7      4     10   6     8     8     9     5     6     4     8 Present this information in a frequency table. Solution: To construct a frequency table, we proceed as follows: Step 1: Construct a table with three columns.  The first column shows what is being arranged in ascending order (i.e. the marks).  The lowest mark is 4.  So, start from 4 in the first column as shown below. Step 2: Go through the list of marks.  The first mark in the list is 6, so put a tally mark against 6 in the second column.  The second mark in the list is 7, so put a tally mark against 7 in the second column.  The third mark in the list is 5, so put a tally mark against 5 in the third column as shown below. We continue this process until all marks in the list are tallied. Step 3: Count the number of tally marks for each mark and write it in third column.  The finished frequency table is as follows:

 Question: Make a data with a frequency table in Microsoft Excel and upload it on the comments (Individual data). 

pH Scale

pH Scale

pH Scale

• pH is a measure of how acidic or basic a solution is.
• The pH scale ranges from 0 to 14.
• Acidic solutions have pH values below 7
• A solution with a pH of 0 is very acidic.
• A solution with a pH of 7 is neutral.
• Pure water has a pH of 7.
• Basic solutions have pH values above 7.
• A change of 1 pH unit represents a tenfold change in the acidity of the solution.
•  For example, if one solution has a pH of 1 and a second solution has a pH of 2, the first solution is not twice as acidic as the second—it is ten times more acidic

pH Scale