Two coins are tossed. Find the probability that two heads are obtained.

From a class of $12$ girls and $18$ boys,two students are chosen randomly. What is the probability that both of them are girls?

$A$ dice is rolled and a coin is tossed. Find the probability that the die shows an odd number and the coin shows a head.

Bag $A$ contains $4$ green and $3$ red balls and bag $B$ contains $4$ red and $3$ green balls. One bag is selected at random and a ball is drawn,which is found to be green. What is the probability that it came from bag $B$?

The chance of throwing a total of $7$ or $12$ with $2$ dice is:

In a single throw of $2$ dice,find the probability of getting a total of $3$ or $5$.