Three dice are thrown simultaneously. What is the probability of obtaining a total of $17$ or $18$?

Three boxes contain respectively $3$ white and $1$ black,$2$ white and $2$ black,$1$ white and $3$ black balls. From each of the boxes,one ball is drawn at random. The probability that $2$ white and $1$ black balls will be drawn is:

If there are $4$ red,$3$ pink,$5$ yellow,and $8$ white roses in a garden,what is the probability that a blind person touches a red or a white rose?

The probability that a non-leap year selected at random will contain $52$ Saturdays or $53$ Sundays is

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

Let $S$ be a set containing $n$ elements. If we select $2$ subsets $A$ and $B$ of $S$ at random,then the probability that $A \cup B = S$ and $A \cap B = \phi$ is: