The number of ways in which any four letters can be selected from the word ‘$CORGOO$’ is
$15$
$11$
$7$
None of these
If $^{15}{C_{3r}}{ = ^{15}}{C_{r + 3}}$, then the value of $r$ is
In a touring cricket team there are $16$ players in all including $5$ bowlers and $2$ wicket-keepers. How many teams of $11$ players from these, can be chosen, so as to include three bowlers and one wicket-keeper
How many numbers greater than $1000000$ can be formed by using the digits $1,2,0,2,4,2,4 ?$
There were two women participating in a chess tournament. Every participant played two games with the other participants. The number of games that the men played between themselves proved to exceed by $66$ the number of games that the men played with the women. The number of participants is
A man $X$ has $7$ friends, $4$ of them are ladies and $3$ are men. His wife $Y$ also has $7$ friends, $3$ of them are ladies and $4$ are men. Assume $X$ and $Y$ have no comman friends. Then the total number of ways in which $X$ and $Y$ together can throw a party inviting $3$ ladies and $3$ men, so that $3$ friends of each of $X$ and $Y$ are in this party is :