Question

The formula for finding mean by direct method is
$\frac{\sum (A\times B)}{\sum A}$

where B and A are respectively are _______.

• A. class mark, frequency of the class
• B. frequency of the class, class mark
• C. class size, average frequency
• D. average frequency, class size

Answer 1

The correct option is A class mark, frequency of the class

Given, Mean = $\frac{\sum (A\times B)}{\sum A}$........(i)

$\because \text{Mean}\left(\overline{x}\right)=\frac{\sum fx}{\sum f}$ ..........(ii)

where, 'f' is the frequency of a class
'x' is the class mark of the class

Now, comparing (i) and (ii), we get,

'A' is the frequency of the class
and 'B' is the class mark.