0 votes
291 views
in Statistics by (27.3k points)
closed by

A class teacher has the following absentee record of 40 students of a class for the whole term. Find the mean number of days a student was absent.

 Number of days:  0 - 6  6 - 10  10 - 14  14 -20  20 - 28  28 - 38  38 - 40
 Number of students:  11  10  7  4  4  3  1

1 Answer

+1 vote
by (26.1k points)
selected by
 
Best answer

We may calculate class marks (xi) for each interval by using the relation

xi \(=\frac{Upper\,class\,limit+lower\,class\,limit}{2}\)

Now taking assumed mean (A) = 16

 Number of days   Number of students (fi)  xi  di = xi - 16 fidi
 0 - 6  11 3 -13 -143
 6 - 10  10 5 -8 -80
10 - 14  7 12 -4 -28
14 - 20 4 16 0 0
20 - 28 4 24 8 32
28 - 38 3 33 17 51
38 - 40 1 39 23 23
 N = 40 \(\sum\)fidi = -145

Mean (x̅) = A + \(\frac{\sum fidi}{N}\)

\(=16+\frac{-145}{40}\)

\(=16 - 3.62=12.38\)

So, 

mean number of days is 12.38 days for which students were absent.

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.

Categories

...