A) \[\frac{1}{n}\]
B) \[\sqrt{2}\]
C) 2
D) \[\frac{\sqrt{2}}{n}\]
Correct Answer: C
Solution :
[c] In the 2n observations, half of them equal to a and the remaining half equal to ? a. then the mean of total 2n observations is equal to zero. Therefore, \[S.D.=\sqrt{\frac{\Sigma \,{{(x-x)}^{2}}}{N}}\] \[2=\sqrt{\frac{\Sigma {{x}^{2}}}{2n}}\] \[\Rightarrow 4=\frac{\Sigma {{x}^{2}}}{2n}\] \[\Rightarrow 4=\frac{2{{a}^{2}}}{2n}\] \[\Rightarrow {{a}^{2}}=4\] \[\Rightarrow \left| a \right|=2\]
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