In a binomial distribution,the probability of success is $\frac{1}{4}$ and the standard deviation is $3$. Find its mean.

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

Suppose $X$ follows a binomial distribution with parameters $n$ and $p$,where $0 < p < 1.$ If $\frac{P(X = r)}{P(X = n - r)}$ is independent of $n$ and $r$,then

If $X$ follows a binomial distribution with parameters $n = 6$ and $p$ and $4(P(X = 4)) = P(X = 2)$,then $p = $

In $3$ trials of a binomial distribution,the probability of $2$ successes is $9$ times the probability of $3$ successes. Then the probability of success in each trial is

If the probability of hitting a target by a shooter,in any shot,is $\frac{1}{3}$,then the minimum number of independent shots at the target required by him so that the probability of hitting the target at least once is greater than $\frac{5}{6}$,is