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

The probabilities of a student getting $I, II$ and $III$ division in an examination are respectively $\frac{1}{10}, \frac{3}{5}$ and $\frac{1}{4}$. The probability that the student fails in the examination is

Two fair dice are tossed. Let $A$ be the event that the first die shows an even number and $B$ be the event that the second die shows an odd number. The two events $A$ and $B$ are

$A$ person draws a card from a pack of playing cards,replaces it and shuffles the pack. He continues doing this until he draws a spade. The chance that he will fail in the first two attempts is

$A$ bag contains $6$ red,$4$ white and $8$ blue balls. If three balls are drawn at random,then the probability that $2$ are white and $1$ is red,is

$A$ coin is tossed and a dice is rolled. The probability that the coin shows the head and the dice shows $6$ is