$A$ coin is tossed $7$ times. What is the probability that a person who calls 'heads' every time wins more often?

If the mean and variance of a binomial variable $X$ are $2$ and $1$ respectively,then what is the probability that $X \geq 1$?

$A$ random variable $X$ follows a binomial distribution in which the difference between its mean and variance is $1$. If $2 P(X=2)=3 P(X=1)$,then $n^2 P(X>1)=$

Two cards are drawn successively with replacement from a well-shuffled pack of $52$ cards. Let $X$ denote the random variable of the number of jacks obtained in the two drawn cards. Then $P(X=1) + P(X=2)$ equals

$A$ box contains $15$ green and $10$ yellow balls. If $10$ balls are randomly drawn,one-by-one,with replacement,then the variance of the number of green balls drawn is:

Two cards are drawn successively with replacement from a fair deck of $52$ cards. Let $X$ denote the number of kings obtained when two cards are drawn. Then $E(X^2) = $