probability Questions

The probability that $A$ speaks truth is $\frac{4}{5},$ while this probability for $B$ is $\frac{3}{4}.$ The probability that they contradict each other when asked to speak on a fact is

A random variable $X$ has the probability distribution:

For the events $E=\{X\text{ is a prime number}\}$ and $F=\{X<4\},$ the probability $P(E\cup F)$ is

The mean and the variance of a binomial distribution are $4$ and $2$ respectively. Then the probability of $2$ successes is

The number of ways of distributing $8$ identical balls in $3$ distinct boxes so that none of the boxes is empty is