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Determine $\text{E}(X)$ and $\mathrm{Var}(X)$.
Mathematics 9709 · AS & A Level · Sampling and estimation
Sampling and estimation — practice question
A box holds $2$ green sweets and $5$ blue sweets. Two sweets are chosen at random from the box, without replacement. The random variable $X$ represents the number of green sweets chosen.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Make an attempt to obtain probabilities like $P(X=0)=P(B,B)=\frac{5}{7} \times \frac{4}{6} = \frac{10}{21}$” …
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