Example1 The marks obtained by 30 students of

Example-1 The marks obtained by 30 students of Class X of a certain school in a Mathematics paper consisting of 100 marks are presented in table below. Find the mean of the marks obtained by the students by using Direct Method.

Solution

Example-2 The marks obtained by 30 students of Class X of a certain school in a Mathematics paper consisting of 100 marks are presented in table below. Find the mean of the marks obtained by the students by using Assumed Mean Method.

Solution

• Calculate the deviations of all xi’s from ‘a’ as di = xi - a. • Divide all di’s by a common factor h( ideally h should be the size of classes) as ui = di/h. • Take the product of all ui’s with the corresponding fi’s. • Take the sum of all fi’s and fiui’s. • Use the formula below to find the mean of the data.

Example-3 The marks obtained by 30 students of Class X of a certain school in a Mathematics paper consisting of 100 marks are presented in table below. Find the mean of the marks obtained by the students by using Step Deviation Method.

Solution

Example 4 Consider a grouped frequency distribution of marks obtained, out of 100, by 53 students, in a certain examination, as follows: Find the median of the data.

Solution

Example - 5 A survey conducted on 20 households in a locality by a group of students resulted in the following frequency table for the number of family members in a household: Find the mode of this data.