Solution : Here the minimum and maximum numerical values of the data of
temperature are 6 and 14 respectively.
Hence the range = 14 6 + 1 = 9.
If the class interval is considered to be 3, the numbers of class will be
3
9
or, 3.Considering 3 to be the class interval, if the data are arranged in 3 classes, the
frequency table will be :
Temperature (in celcius) Tally Frequency
6 q 8 q llll llll l 11
9 q 11 q llll llll lll 13
12 q 14 q llll ll 7
Total = 31Activity : Form two groups of all the students studying in your class. Find the
frequency distribution table of the weights (in Kgs) of all the members of the
groups.Cumulative Frequency :
In example1, considering 3 the class interval and determining the number of classes,
the frequency distribution table has been made. The numbers of classes of the
mentioned data are 3. The limit of the first class is 6q 8 q. The lowest range of the
class is 6o and the highest range is 8oC. The frequency of this class is 11.
The frequency of the second class is 13. Now if the frequency 11 of first class is
added to the frequency 13 of the second class, we get 24. This 24 will be the
cumulative frequency of the second class and the cumulative frequency of first class
as begins with the class will be 11. Again, if the cumulative frequency 24 of the
second class is added to the frequency of the third class, we get 24 + 7 = 31 which is
the cumulative frequency of the third class. Thus cumulative frequency distribution
table is made. In the context of the above discussion, the cumulative frequency
distribution of temperature in example 1 is as follow :
Temperature (in celsius) Frequency Cumulative Frequency
6 q 8 q 11 11
9 q 11 q 13 (11 + 13) = 24
12 q 14 q 7 (24 + 7) = 31
Example 2. The marks obtained in English by 40 students in an annual examination
are given below. Make a cumulative frequency table of the marks obtained.
70, 40, 35, 60, 55, 58, 45, 60, 65, 80, 70, 46, 50, 60, 65, 70, 58, 69, 48, 70, 36, 85,
60, 50, 46, 65, 55, 61, 72, 85, 90, 68, 65, 50, 40, 56, 60, 65, 46, 76.