Mathematics 9709 · AS & A Level · Discrete random variables
Discrete random variables — practice question
An ordinary fair die is rolled repeatedly until a $6$ appears.
(a)[2]
Find the probability that it takes more than $8$ throws to obtain a $6$.
(b)[1]
Two ordinary fair dice are rolled together until a pair of $6$s is obtained. The number of throws required is represented by the random variable $X$. Find the expected value of $X$.
(c)[2]
Find the probability that it takes either $10$ or $11$ throws to obtain a pair of $6$s.
Worked solution & mark scheme
This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Right expression $(\frac{5}{6})^8$” …