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    A biased coin has probability 0.4 of showing a head. In an experiment, the coin is spun
    until a head appears. If a head has not appeared after 4 spins, the coin is not spun again. The random variable X represents the number of times the coin is spun. For example, X = 3 if the first two spins do not show a head but the third spin does show a head. The coin would not then be spun a fourth time since the coin has already shown a head.
    (a) Show that P(X = 3) = 0.144
    The table gives some values for the probability distribution of X
    x = 1 2 3 4
    P(X = x)= 0.24 0.144
    (b) (i) Write down the value of P(X = 1) (ii) Find P(X = 4)
    (c) Find E(X ) (2) (d) Find Var(X )
    The random variable H represents the number of heads obtained when the coin is spun in the experiment.
    (e) Explain why H can only take the values 0 and 1 and find the probability distribution of H.
    (f) Write down the value of
    (i) P({X = 3} ∩ {H = 0})
    (ii) P({X = 4} ∩ {H = 0})
    The random variable S = X + H
    (g) Find the probability distribution of S
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    working out..?
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    (Original post by Radioactivedecay)
    working out..?
    i dont know how to continue from part -e-
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    H means that when you spin a coin how many heads to you get:
    • If you spin the coin and land on tails then H=0
    • If you spin the coin and land on heads then H=0

    p(H=0)=p(land on a tail)
    p(H=1)=p(land on a head)
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    (Original post by lili4648)
    H means that when you spin a coin how many heads to you get:
    • If you spin the coin and land on tails then H=0
    • If you spin the coin and land on heads then H=0

    p(H=0)=p(land on a tail)
    p(H=1)=p(land on a head)
    yes and part -f- ?
 
 
 
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