A) \[78'\]
B) \[186\]
C) \[158\]
D) \[18\]
Correct Answer: A
Solution :
Given, \[\Sigma {{x}^{2}}=2830,\,\,\Sigma x=170\] and \[n=15\] Now, the correct \[\Sigma x=170-20+30\] \[=180\] and correct \[\Sigma {{x}^{2}}=2830-{{(20)}^{2}}+{{(30)}^{2}}\] \[=2830-400+900\] \[=2830+500=3330\] \[\therefore \] Correct variance \[=\frac{\Sigma {{x}^{2}}}{n}-{{\left( \frac{\Sigma x}{2} \right)}^{2}}=\frac{3330}{15}-{{\left( \frac{180}{15} \right)}^{2}}\] \[=222-{{(12)}^{2}}=222-144\] \[=78\]
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