$5\mathrm{.}62$ In Example $5\mathrm{.}7$ above, a financial analyst was facing the

task of selecting mutual funds to purchase for a client's portfolio.

Suppose that the number of funds had been narrowed to $12$ funds

instead of the $10$ funds $($still with $6$ growth funds$)$ in Example $5\mathrm{.}7.$

What is the probability that of the $4$ funds selected,

a$.$ exactly $1$ is a growth fund?

b$.$ at least $1$ is a growth fund?

c$.3$ are growth fund?

d$.$ Compare the result of $($c$)$ to the result of Example $5\mathrm{.}7.$