$A$ coin is tossed $3$ times. Find the chance that head and tail show alternately.

If letters of the word $PENCIL$ are arranged in random order,what is the probability that $N$ is always next to $E$?

There are $3$ urns $A, B$,and $C$. Urn $A$ contains $4$ red balls and $3$ black balls. Urn $B$ contains $5$ red balls and $4$ black balls. Urn $C$ contains $4$ red balls and $4$ black balls. One ball is drawn from each of these urns. What is the probability that the $3$ balls drawn consist of $2$ red balls and $1$ black ball?

$A$ Chartered Accountant applies for a job in $2$ firms $X$ and $Y$. The probability of his being selected in firm $X$ is $0.7$,and being rejected at $Y$ is $0.5$,and the probability of at least $1$ of his applications being rejected is $0.6$. What is the probability that he will be selected in $1$ of the firms?

$2$ dice are thrown. Find the odds against getting the sum $6$.

$A$ man and his wife appear for an interview for two posts. The probability of the husband's selection is $\frac{1}{7}$ and that of the wife's selection is $\frac{1}{5}$. What is the probability that only one of them will be selected?