(i)[5]
Construct the probability distribution table for the number of heads that are obtained.
(ii)[3]
Hence calculate the mean and variance for the number of heads obtained.
Mathematics 9709 · AS & A Level · Linear combinations of random variables
Linear combinations of random variables — practice question
A game uses $3$ coins, $A$, $B$ and $C$. Coins $A$ and $B$ are biased so that the chance of getting a head is $0.4$ for coin $A$ and $0.75$ for coin $B$. Coin $C$ is unbiased. The $3$ coins are tossed once.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “The probabilities for $0,1,2,3$ heads have been identified.” …
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