Question

The following table gives the number of boys of a particular age in a class of 40 students. Calculate the mean age of the students.
Age(in year): 15 16 17 18 19 20No.of students: 3 8 10 10 5 4

Answer 1

age in years Xi       no. of students Fi       XiFi  

    15                                  3                         45

    16                                  8                         128

    17                                  10                        170

    18                                  10                        180

    19                                   5                         95

    20                                 4                          80

total sum of XiFi = 698

sum of Fi = 40

mean = total sum of XiFi / total number of student

         = 698/40

         = 17.45

Answer 2

Given:

Age(in year): 15 16 17 18 19 20No.of students: 3 8 10 10 5 4

To find:

The mean of the number of boys

Answer:

1. The frequency of the number of students pertaining to different ages is tabulated and the solution is attached below.

2. The formula for weighted mean is:

Mean = summation (XiFi)/ summation (Fi).

where,

Xi is the age of ith observation

Fi is the frequency of ith observation

Mean= (45 +128 +170 +180 +95 +80)/40

Mean = 17.45 years

The mean of the number of boys of a particular age in a class of 40 students is 17.45 years.