There are $n$ letters and $n$ addressed envelops. The probability that each letter takes place in right envelop is

From a group of $7$ men and $4$ ladies a committee of $6$ persons is formed, then the probability that the committee contains $2$ ladies is

Seven white balls and three black balls are randomly placed in a row. The probability that no two black balls are placed adjacently equals

A bag contains $4$ white and $3$ red balls. Two draws of one ball each are made without replacement. Then the probability that both the balls are red is

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

When a missile is fired from a ship, the probability that it is intercepted is $\frac{1}{3}$ and the probability that the missile hits the target, given that it is not intercepted, is $\frac{3}{4}$. If three missiles are fired independently from the ship, then the probability that all three hit the target, is