Two cards are drawn successively with replacement from a well-shuffled pack of $52$ cards. The mean of the number of queens is:

If on an average $9$ mountain climbers out of $10$ return safely,what is the probability that with $5$ climbers out,at least $4$ will return safely?

Two cards are drawn successively with replacement from a well-shuffled pack of $52$ cards. The mean of the number of kings is:

In a multiple-choice examination, there are $10$ questions with one correct option out of $4$ options for each question. $A$ student gets $4$ marks for each correct answer and $1$ mark is deducted for each incorrect answer. The probability that a student, guessing randomly on every question, scores $30$ marks in this exam is... (in $/4^{10}$)

Find the probability of getting $5$ exactly twice in $7$ throws of a die.

In a tournament,a team plays $10$ matches with probabilities of winning and losing each match as $\frac{1}{3}$ and $\frac{2}{3}$ respectively. Let $x$ be the number of matches that the team wins,and $y$ be the number of matches that the team loses. If the probability $P(|x-y| \leq 2)$ is $p$,then $3^9 p$ equals....................