$A$ bag contains $3$ white and $2$ black balls and another bag contains $2$ white and $4$ black balls. $A$ ball is picked up randomly. The probability of its being black is

$2$ dice are thrown. Find the probability of getting a sum more than $7$.

$A$ card is drawn from an ordinary pack and a gambler bets that it is a spade or an ace. What are the odds against his winning the bet?

$A$ husband and wife appear in an interview for $2$ vacancies in the same post. The probability of the husband's selection is $\frac{1}{7}$ and that of the wife's is $\frac{1}{5}$. What is the probability that both of them will be selected?

An urn contains $25$ balls numbered $1$ to $25$. Suppose an odd number is considered a 'success'. $2$ balls are drawn from the urn with replacement. Find the probability of getting no success.

$A$ letter is known to have come either from $LONDON$ or $CLIFTON$; on the postmark only the two consecutive letters $ON$ are legible. The probability that it came from $LONDON$ is