In a box,there are $8$ red,$7$ blue,and $6$ green balls. One ball is picked up at random. What is the probability that it is neither red nor green?

$A$ word consists of $11$ letters in which there are $7$ consonants and $4$ vowels. If $2$ letters are chosen at random,then the probability that both of them are consonants is:

$A$ box contains $10$ identical electronic components,of which $4$ are defective. If $3$ components are selected at random from the box in succession,without replacement,what is the probability that exactly two components of the selected components are defective?

If $A$ is a sure event,then the value of $P(A^c)$ is

$A$ and $B$ throw a coin alternately till $1$ of them gets a head and wins the game. If $A$ starts the game,find the probability of $A$ winning.

Three houses are available in a locality. Three persons apply for the houses. Each applies for one house without consulting others. The probability that all the three apply for the same house is