In a college, $25\%$ of the boys and $10\%$ of the girls offer Mathematics. The girls constitute $60\%$ of the total number of students. If a student is selected at random and is found to be studying Mathematics, the probability that the student is a girl, is

If in a lottary there are $5$ prizes and $20$ blanks, then the probability of getting a prize is

Two dice are thrown. The events $A, B$ and $C$ are as follows:

$A:$ getting an even number on the first die.

$B:$ getting an odd number on the first die.

$C:$ getting the sum of the numbers on the dice $\leq 5$

Describe the events  $B$ and $C$

The probability that a teacher will give an unannounced test during any class meeting is $1/5$. If a student is absent twice, then the probability that the student will miss at least one test is

In order to get at least once a head with probability $ \ge 0.9,$ the number of times a coin needs to be tossed is

Three fair coins are tossed. If both heads and tails appears, then the probability that exactly one head appears, is