Four persons are selected at random from a group of $3$ men,$2$ women and $4$ children. The chance that exactly two of them are children is

In a single throw of two dice,what is the probability of obtaining a sum of numbers greater than $7$,given that $4$ appears on the first die?

The probability of drawing a white ball from a bag containing $3$ black balls and $4$ white balls is:

Study the given information carefully and answer the questions that follow: $A$ basket contains $4$ red,$5$ blue and $3$ green marbles. If $3$ marbles are picked at random,what is the probability that either all are green or all are red?

While dialing a telephone number,an old man forgets the last two digits,remembering only that they are different. If he dials the last two digits at random,what is the probability that the number is dialed correctly?

For independent events $A_1, A_2, \dots, A_n$, $P(A_i) = \frac{1}{i + 1}$ for $i = 1, 2, \dots, n$. Then the probability that none of the events will occur is: