$(12$ pts$)$

a$)$ How many ways are there to select $4$ students from a class of $30$ to serve on a

committee? $(4$ pts$)$

b$)$ How many ways are there to select $4$ students from a class of $30$ to hold four different

executive positions on a committee? $(4$ pts$)$

c$)$ How many bit strings of length $12$ have equal numbers of $0\text{'}$s and $1\text{'}$s$?(4$ pts$)$