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Home  >>  CBSE XI  >>  Math  >>  Statistics
0 votes

Find mean and variance of the data:

$\begin{array}{1 1}(A)\;29.09\\(B)\;43.4\\(C)\;4.89\\(D)\;5.125\end{array} $

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1 Answer

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Toolbox:
  • To calculate Mean $\bar{x}= \large\frac{\sum f_i x_i}{\sum f_i}$
  • Variance $=\large\frac{\sum x_i^2}{n} - \bigg(\large\frac{\sum x_i}{n} \bigg)^2$
Step 2:
Mean $\bar{x}= \large\frac{\sum f_i x_i}{\sum f_i}$
$\qquad= \large\frac{2200}{22}$$=100$
Step 3:
Variance $=\large\frac{\sum x_i^2}{n} - \bigg(\large\frac{\sum x_i}{n} \bigg)^2$
$\qquad= \large\frac{\sum f_ix_i^2}{\sum f_i} - \bigg( \large\frac{\sum f_i x_i}{\sum f_i} \bigg)^2$
$\qquad= 10029.09-10000$
$\qquad= 29.09$
Hence A is the correct answer.
answered Jun 27, 2014 by meena.p
 
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