(i)[3]
Calculate $\Sigma (x - 50)$ and $\Sigma (x - 50)^2$.
(ii)[3]
One person took the test later and scored $72$. Calculate the new mean and standard deviation for the marks of all $17$ people.
Mathematics 9709 · AS & A Level · Sampling and estimation
Sampling and estimation — practice question
Esme recorded the test marks, $x$, for a class of $16$. She determined that $\Sigma x = 824$ and that the standard deviation of $x$ was $6.5$.