A committee of $7$ has to be formed from $9$ boys and $4$ girls. In how many ways can this be done when the committee consists of:
at least $3$ girls?
since at least $3$ girls are to be there in every committee, the committee can consist of
$(a)$ $3$ girls and $4$ boys or
$(b)$ $4$ girls and $3$ boys
$3$ girls and $4$ boys can be selected in $^{4} C_{3} \times^{9} C_{4}$ ways.
$4$ girls and $3$ boys can be selected in $^{4} C_{4} \times^{9} C_{3}$ ways.
Therefore, in this case, required number of ways $=^{4} C_{3} \times^{9} C_{4}+^{4} C_{4} \times^{9} C_{3}$
$=504+84=588$
What is the number of ways of choosing $4$ cards from a pack of $52$ playing cards? In how many of these
four cards are of the same suit,
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
Out of $6$ books, in how many ways can a set of one or more books be chosen
The total number of different combinations of one or more letters which can be made from the letters of the word ‘$MISSISSIPPI$’ is
Let the number of elements in sets $A$ and $B$ be five and two respectively. Then the number of subsets of $A \times B$ each having at least $3$ and at most $6$ element is :