JEE Mains · Maths · STD 11 - 13. statistics
If \(\mathop \sum \limits_{i = 1}^9 \left( {{x_i} - 5} \right) = 9\) and \(\mathop \sum \limits_{i = 1}^9 {\left( {{x_i} - 5} \right)^2} = 45,\) then the standard deviation of the \(9\) items \({x_1},{x_2},\;.\;.\;.\;,{x_9}\) is :
- A \(4\)
- B \(2\)
- C \(3\)
- D \(9\)
Answer & Solution
Correct Answer
(B) \(2\)
Step-by-step Solution
Detailed explanation
Given \(\sum\limits_{i = 1}^9 {\left( {{x_i} - 5} \right)} = 9 \Rightarrow \sum\limits_{i = 1}^9 {{x_i} = 54\,\,\,.....\left( i \right)} \) Also, \(\sum\limits_{i = 1}^9 {{{\left( {{x_i} - 5} \right)}^2}} = 45\)…
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