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Find mean and variance of the data:

$\begin{array}{1 1}(A)\;2\\(B)\;43.4\\(C)\;4\\(D)\;0\end{array} $

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1 Answer

Step 2:
Mean $= \large\frac{\sum f_i x_i}{\sum f_i}$
$\qquad= \large\frac{760}{40}$
$\qquad=19$
Step 3:
Variance $=\large\frac{\sum x_i^2}{n} - \bigg(\large\frac{\sum x_i}{n} \bigg)^2$
$\qquad= \large\frac{16176}{40} =\bigg( \large\frac{760}{40}\bigg)$
$\qquad= 404.4 - (19)^2$
$\qquad= 404.4-361$
$\qquad= 43.4$
Hence B is the correct answer.
answered Jun 27, 2014 by meena.p
 
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