(a)[2]
Determine the standard deviation for these values of $x$.
(b)[2]
Using $\sum x = 2865$, determine the value of $q$.
Mathematics 9709 · AS & A Level · Representation of data
Representation of data — practice question
For 50 values of $x$, the totals are $\sum (x - q) = 700$ and $\sum (x - q)^2 = 14\,235$, with $q$ as a constant.
Worked solution & mark scheme
This 4-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Correct application of the variance formula $\displaystyle \text{Var}=\frac{\sum (x-q)^2}{50}-\left(\frac{\sum (x-q)}{50}\right)^2$ (or an equivalent form such as $\frac{14235}{50}-\left(\frac{700}{50}\right)^2$).” …
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