Mathematics 9709 · AS & A Level · Discrete random variables

Discrete random variables — practice question

Hazeem keeps throwing two standard fair 6-sided dice together. Each time, the result is the total of the two numbers she gets.
(a)[2]

Find the probability that it takes exactly 5 throws of the two dice for Hazeem to obtain a score of $8$ or more.

(b)[2]

Find the probability that Hazeem takes no more than 4 throws of the two dice to get a score of $8$ or more.

(c)[3]

For $8$ throws chosen at random from the two dice, find the probability that Hazeem gets a score of $8$ or more on fewer than $3$ occasions.

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: Applies the binomial expression $(\frac{21}{36})^4(\frac{15}{36})$ or $(1-p)^4p$.

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