It looks like you are using Excel? The range of the data is simply [min, max]. Divide the length of that range by five and you have five uniform classes.
Q: # 1:
The output in units of 20 employees during one week was as follows:
65, 69, 70, 71, 70, 68, 69, 67, 70, 68
72, 71, 69, 74, 70, 73, 71, 67, 69, 70
a) Arrange them in ascending order using “Sort Ascending” option in tool bar or from Data menu and also find the number of data elements by using COUNT function.
b) Find range of data.
c) Start doing tabulation of given data. Make 5 classes by using suitable class interval.
d) Make the frequency distribution.
e) Also make the column of class mark.
f) Also find out the mean by constructing relevant column “f X”
g) Also compute relative frequency distribution and cumulative frequency distribution.