Mathematics 9709 · AS & A Level · Discrete random variables

Discrete random variables — practice question

A coin is loaded so that the chance of a head on any throw is 0.4. The coin keeps being thrown until the first head comes up.
(a)[1]

Find the probability that the first head comes up on the 5th throw.

(b)[2]

Find the probability that the first head comes up after the 6th throw.

Worked solution & mark scheme

This 3-mark question has a full step-by-step worked solution and mark scheme. One marking point: “This gives $[(0.6)^4(0.4)] = 0.05184 = \frac{162}{3125}$” …

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