(i)[2]
Calculate the standard deviation of these $x$ values.
(ii)[2]
Given that the mean of these values is $86$, determine the value of $c$.
Mathematics 9709 · AS & A Level · Sampling and estimation
Sampling and estimation — practice question
For 30 values of $x$, the following totals were obtained: $\sum (x-c) = 234$, $\sum (x-c)^2 = 1957.5$, where $c$ is a constant.
Worked solution & mark scheme
This 4-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Substitute into the standard deviation formula or expand: $s^2 = \frac{1957.5}{30} - \left(\frac{234}{30}\right)^2$” …
- Full mark scheme, point by point
- Step-by-step worked solution
- Write your answer & get it marked instantly by AI