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

The probability that a missile hits a target successfully is $0.75$. In order to destroy the target completely,at least three successful hits are required. Then the minimum number of missiles that have to be fired so that the probability of completely destroying the target is $NOT$ less than $0.95$,is. . . . .

$A$ person buys a lottery ticket in $50$ lotteries,in each of which his chance of winning a prize is $\frac{1}{100}$. What is the probability that he will win a prize at least once?

Each of the persons $A$ and $B$ independently tosses three fair coins. The probability that both of them get the same number of heads is:

$A$ and $B$ are playing a chess game with each other. The probability that $A$ wins the game is $0.6$,the probability that he loses is $0.3$,and the probability that it is a draw is $0.1$. If they play three games,what is the probability that $A$ wins at least two games?

$A$ coin is tossed $n$ times. The probability of getting a head at least once is greater than $0.8$. Then, the least value of such $n$ is: