Question

The marks obtained by the students of a class , in an exam which was out of 50 marks is given below :

$\begin{array}{cc}Marks& Numberofstudents\\ 5& 1\\ 7& 2\\ 11& 2\\ 16& 3\\ 21& 5\\ 24& 6\\ 28& 3\\ 32& 5\\ 34& 8\\ 39& 6\\ 43& 4\\ 45& 2\\ 49& 3\end{array}$

Find the mean for the ungrouped data.

• A. 29.94
• B. 24
• C. 28
• D. 30.5

Answer 1

The correct option is A 29.94

$\begin{array}{ccc}{x}_i& f_i& f_i{x}_i\\ 5& 1& 5\\ 7& 2& 14\\ 11& 2& 22\\ 16& 3& 48\\ 21& 5& 105\\ 24& 6& 144\\ 28& 3& 84\\ 32& 5& 160\\ 34& 8& 272\\ 39& 6& 234\\ 43& 4& 172\\ 45& 2& 90\\ 49& 3& 147\end{array}$

$\sum f_i=50$ and $\sum f_i{x}_i=1497$

$\therefore Mean=\frac{\sum f_i{x}_i}{\sum f_i}=\frac{1497}{50}$
$=29.94$