Mathematics 9709 · AS & A Level · Linear combinations of random variables

Linear combinations of random variables — practice question

This fair triangular spinner has sides labelled 1, 2 and 3. Each spin gives the number shown on the side it lands on. It is spun four times.

(i)[3]

Calculate the probability that at least two of the scores are 3.

(ii)[3]

Calculate the probability that the four scores have a total of $5$.

Worked solution & mark scheme

This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Take $p=\tfrac13$ and the suitable binomial term” …