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