A) 78.00
B) \[188.66\]
C) \[177.33\]
D) \[8.33\]
Correct Answer: A
Solution :
[a] Given \[\Sigma x=170,\Sigma {{x}^{2}}=2830\] Increase in \[\Sigma x=10,\] then \[\Sigma x'=170+10=180\] Increase in \[\Sigma {{x}^{2}}=900-400=500,\] then \[\Sigma x{{'}^{2}}=2830+500=3330\] \[\therefore \] Variance \[=\frac{1}{n}\Sigma x{{'}^{2}}-{{\left( \frac{\Sigma x'}{n} \right)}^{2}}\] \[=\frac{3330}{15}-{{\left( \frac{180}{15} \right)}^{2}}=222-144=78.\]
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