The chance of getting a doublet with $2$ dice is

The probability that a man will be alive $25$ years hence is $0.3$,and the probability that his wife will be alive $25$ years hence is $0.4$. Find the probability that $25$ years hence,only the woman will be alive.

In a class of $25$ students with roll numbers $1$ to $25,$ a student is picked up at random to answer a question. Find the probability that the roll number of the selected student is either a multiple of $5$ or $7$.

$A$ box contains $36$ tickets numbered $1$ to $36$. One ticket is drawn at random. Find the probability that the number on the ticket is either divisible by $3$ or is a perfect square.

$A$ number is chosen at random from the first ten natural numbers. The probability that the number is odd and a perfect square is

You are given the digits $2, 3, 4, 6,$ and $7$. In how many ways can you form a $3$-digit number without repetition of digits that is odd and greater than $300$?