Two squares are chosen at random on a chessboard (see figure). The probability that they have a side in common is :
$\frac{2}{7}$
$\frac{1}{18}$
$\frac{1}{7}$
$\frac{1}{9}$
If $10$ different balls are to be placed in $4$ distinct boxes at random, then the probability that two of these boxes contain exactly $2$ and $3$ balls is
A bag contains $8$ black and $7$ white balls. Two balls are drawn at random. Then for which the probability is more
Six boys and six girls sit in a row. What is the probability that the boys and girls sit alternatively
A bag contains twelve pairs of socks and four socks are picked up at random. The probability that there is at least one pair is equal to
Three randomly chosen nonnegative integers $x, y$ and $z$ are found to satisfy the equation $x+y+z=10$. Then the probability that $z$ is even, is