Mathematics 9709 · AS & A Level · Sampling and estimation
Sampling and estimation — practice question
For one Art class, the ages of $12$ people have a mean of $48.7$ years and a standard deviation of $7.65$ years. For another Art class, the ages of $7$ people have a mean of $38.1$ years and a standard deviation of $4.2$ years.
(i)[2]
Calculate the mean age for all $19$ people.
(ii)[4]
Let the individual ages in years of the people in the first Art class be $x$, and those in the second Art class be $y$. By finding $\Sigma x^2$ and $\Sigma y^2$ first, find the standard deviation of the ages of all $19$ people.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Mean expression: $.7\times12+38.1\times7\ndefau19$” …