A) 9
B) 4
C) 3
D) 2
Correct Answer: D
Solution :
[d]: Clearly, \[\sum\limits_{i=1}^{9}{{{x}_{i}}-45=9}\Rightarrow \sum\limits_{i=1}^{9}{{{x}_{i}}=45}\] Now,\[\sum\limits_{i=1}^{9}{x_{i}^{2}-10\times 54+25\times 9=45}\] \[\Rightarrow \]\[\sum\limits_{i=1}^{9}{x_{i}^{2}=360}\] \[\therefore \]\[\sigma =\sqrt{\frac{360}{9}-{{\left( \frac{54}{9} \right)}^{2}}}=2\]You need to login to perform this action.
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