An unbiased die is tossed $500$ times. The standard deviation of getting sixes in these $500$ tosses is

In a binomial distribution,the probability of success is $\frac{1}{4}$ and the standard deviation is $3$. Then,its mean is

$A$ target is to be destroyed in a bombing exercise and there is a $75 \%$ chance that a bomb will hit the target. Assuming that two direct hits are required to destroy the target completely, the minimum number of bombs to be dropped in order that the probability of destroying the target is not less than $99 \%$, is

In a binomial distribution,the mean is $15$ and the variance is $10$. Then the parameter $n$ is:

$A$ die is tossed thrice. $A$ success is defined as getting $1$ or $6$ on a toss. Find the mean and the variance of the number of successes.

$A$ fair coin is tossed $100$ times. The probability of getting tails an odd number of times is