Two dice are thrown simultaneously. If $X$ denotes the number of sixes,then the expectation of $X$ is

The probability that an event will fail to happen is $0.05$. The probability that the event will take place on $4$ consecutive occasions is

In tossing $10$ coins,the probability of getting exactly $5$ heads is

If there are $n$ independent trials,$p$ and $q$ are the probability of success and failure respectively,then what is the probability of exactly $r$ successes?

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

If $X$ has a binomial distribution,$B(n, p)$ with parameters $n$ and $p$ such that $P(X = 2) = P(X = 3)$,then $E(X)$,the mean of variable $X$,is