Four cards are drawn successively with replacement from a well-shuffled deck of $52$ cards. The probability that exactly two cards are club cards is: (in $/128$)

The discrete random variables $X$ and $Y$ are independent from one another and are defined as $X \sim B(n_1, 0.5)$ and $Y \sim B(n_2, 0.4)$. If the variance of both $X$ and $Y$ is $6$,then $\sqrt{n_1+n_2}=$

$A$ die is thrown $6$ times. If 'getting an odd number' is a success,what is the probability of at least $5$ successes?

The probability that event $A$ happens in a trial is $0.4$. If three independent trials are made, then the probability that $A$ happens at least once is.......

If a fair coin is tossed five times,then the probability of getting exactly three heads is . . . . . . .

$A$ student writes an examination which contains $8$ true or false questions. If he answers $6$ or more questions correctly,he passes the examination. If the student answers all the questions,then the probability that he fails in the examination is