(a)[4]
Construct the probability distribution table for $X$.
(b)[3]
Find $\mathrm{Var}(X)$.
Mathematics 9709 · AS & A Level · Discrete random variables
Discrete random variables — practice question
Kayla has a bag that contains 3 red marbles, 1 blue marble and 2 green marbles. She chooses one marble at random from the bag and does not put it back. She keeps repeating this procedure until a green marble is obtained. The random variable $X$ is the number of marbles she must choose before obtaining a green marble.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Table of probabilities with the correct $x$ values and at least one probability correct” …
- Full mark scheme, point by point
- Step-by-step worked solution
- Write your answer & get it marked instantly by AI