In a binomial distribution,if $n=4$ and $P(X=0)=\frac{16}{81}$,then $P(X=4)=$

An unbiased coin is tossed $n$ times. If the probability of getting at least one head is greater than $0.8$,then the least value of $n$ is

$A$ coin is tossed $100$ times. What is the probability of getting a head an odd number of times?

Let $C_1$ and $C_2$ be two biased coins such that the probabilities of getting a head in a single toss are $\frac{2}{3}$ and $\frac{1}{3}$,respectively. Suppose $\alpha$ is the number of heads that appear when $C_1$ is tossed twice,independently,and $\beta$ is the number of heads that appear when $C_2$ is tossed twice,independently. Then,the probability that the roots of the quadratic polynomial $x^2 - \alpha x + \beta$ are real and equal is:

$A$ die is thrown $100$ times. If the success is defined as getting an even number,then the variance of the number of successes is:

The mean and variance of a binomial distribution are $x$ and $5$ respectively. If $x$ is an integer,then the possible values for $x$ are