Mathematics 9709 · AS & A Level · Linear combinations of random variables
Linear combinations of random variables — practice question
The table presents the mean and standard deviation of the weights of some turkeys and geese.
(i)[2]
Find the mean weight for the $27$ birds.
(ii)[5]
Let $x_t$ kg stand for the weight of each turkey and $x_g$ kg stand for the weight of each goose. By first finding $\sum x_t^2$ and $\sum x_g^2$, find the standard deviation of the weights of all $27$ birds.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Correct method: multiply $9$ by $18$ and divide by $27$” …