Mathematics 9709 · AS & A Level · Linear combinations of random variables
Linear combinations of random variables — practice question
The table below displays how many rides two students, Fei and Graeme, went on at a fairground.
(i)[2]
Fei’s rides have a mean cost of $\$2.50$ and a standard deviation of the costs of Fei’s rides is $\$0$. Explain why this shows that the roller coaster and the water slide each cost $\$2.50$ per ride.
(ii)[5]
Graeme’s rides have a mean cost of $\$3.76$. Find the standard deviation of the ride costs.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “States that the standard deviation is zero, i.e. $sd = 0$” …