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

$A$ bag contains $5$ white,$7$ black,and $4$ red balls. If three balls are drawn at random from the bag,what is the probability that all three balls are white?

There are $4$ hotels in a town. If $3$ men check into the hotels in a day,then the probability that each checks into a different hotel is

$A$ basket contains $3$ mangoes and $3$ apples. If two fruits are selected at random,what is the probability of getting one mango and one apple?

$A$ bag contains $4$ white,$5$ red and $6$ black balls. If two balls are drawn at random,then the probability that one of them is white is

All the spades are taken out from a pack of cards. From these cards,cards are drawn one by one without replacement until the ace of spades comes. The probability that the ace of spades comes in the $4^{th}$ draw is