$A$ coin is biased so that the head is $3$ times as likely to occur as tail. This coin is tossed until a head or three tails occur. If $X$ denotes the number of tosses of the coin,then the mean of $X$ is

  • A
    $\frac{21}{16}$
  • B
    $\frac{81}{64}$
  • C
    $\frac{15}{16}$
  • D
    $\frac{37}{16}$

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Similar Questions

State which of the following is not a probability distribution of a random variable. Give reasons for your answer.
$X$ $0$ $1$ $2$ $3$ $4$
$P(X)$ $0.1$ $0.5$ $0.2$ $-0.1$ $0.3$

The following is the probability distribution of $X$:
$X$ $0$ $1$ $2$ $3$
$P(X=x)$ $\frac{1+p}{5}$ $\frac{2-2p}{5}$ $\frac{2-p}{5}$ $\frac{2p}{5}$

For a minimum value of $p$,the value of $5 E(X)$ is:

$A$ random variable $X$ has the following probability density function (p.d.f.):
$f(x) = kx(1-x), 0 \leqslant x \leqslant 1$
If $P(X > a) = \frac{20}{27}$,then find the value of $a$.

The probability distribution of a discrete random variable $X$ is given by the following table:
$X = x$$0$$1$$2$$3$$4$
$P(X = x)$$k$$2k$$4k$$2k$$k$

Then the value of $P(X \leq 2)$ is:

$A$ random variable $X$ has the following probability distribution. Find the value of $k$ and the value of $P(3 < X \leq 6)$.
$X = x$$0$$1$$2$$3$$4$$5$$6$$7$$8$
$P(x)$$k$$2k$$3k$$4k$$4k$$3k$$2k$$k$$k$

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