Mathematics 9709 · AS & A Level · Discrete random variables

Discrete random variables — practice question

Ramesh rolls a standard fair die with 6 sides.
(a)[1]

Find the probability that he gets a 4 for the first time on his 8th throw.

(b)[2]

Find the probability that Ramesh needs no more than 5 throws to obtain a 4.

(c)[4]

For 10 randomly selected throws of the two dice, find the probability that Ramesh gets a total below 4 on at least three throws.

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Correct working out of the probability, for example $ (5/6)^7\times 1/6 = 0.0465$ (or an exact equivalent).” …

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