$A$ coin is tossed $4$ times. The probability that at least one head turns up is

Out of $100$ people selected at random,$10$ have a common cold. If five persons are selected at random from the group,then the probability that at most one person will have a common cold is

$A$ die is thrown $100$ times. The standard deviation of getting an even number is:

$A$ random variable $X \sim B(n, p)$. If the values of the mean and variance of $X$ are $18$ and $12$ respectively,then $n = $

The probability of a bomb hitting a bridge is $\frac{1}{2}$ and two direct hits are needed to destroy it. The least number of bombs required so that the probability of the bridge being destroyed is greater than $0.9$ is:

The binomial distribution whose mean is $9$ and whose standard deviation is $\frac{3}{2}$ is equal to