For a binomial distribution with mean $6$ and variance $2$,find $P(X \geq 2)$.

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

In order to get at least one head with a probability $\ge 0.9$,the minimum number of times a coin needs to be tossed is:

$A$ discrete random variable $X$ has the distribution $B(15, p)$. Given that $\operatorname{Var}(X) = 3.15$. Then,the two possible values of $p$ are

The probability that a person who undergoes a bypass surgery will recover is $0.6$. The probability that of the $6$ patients who undergo similar operations,half of them will recover is:

For an initial screening of an entrance exam,a candidate is given $50$ problems to solve. If the probability that the candidate can solve any problem is $\frac{4}{5}$,then the probability that he is unable to solve less than $2$ problems is: