If $^{20}{C_{n + 2}}{ = ^n}{C_{16}}$, then the value of $n$ is
$7$
$10$
$13$
No value
The number of ways in which four letters of the word $‘MATHEMATICS$’ can be arranged is given by
In an examination there are three multiple choice questions and each question has $4 $ choices. Number of ways in which a student can fail to get all answers correct, is
If $^{n} C _{9}=\,\,^{n} C _{8},$ find $^{n} C _{17}$
$^{14}{C_4} + \sum\limits_{j = 1}^4 {^{18 - j}{C_3}} $ is equal to
Find the number of ways of selecting $9$ balls from $6$ red balls, $5$ white balls and $5$ blue balls if each selection consists of $3$ balls of each colour.