(a)[1]
Show, using the relevant outcomes, that $P(X = 7) = 0.2$.
(b)[3]
Draw up a probability distribution table for $X$.
(c)[3]
Find $\operatorname{Var}(X)$.
Mathematics 9709 · AS & A Level · Discrete random variables
Discrete random variables — practice question
Jasmine owns one $5 coin, two $2 coins and two $1 coins. She picks two of these coins at random. The random variable $X$ gives the total value, in dollars, of the two chosen coins.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Correct identification of favourable outcomes (e.g. $[S7]=[S5]+[S]2$)” …
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