Coronary bypass surgery: A healthcare research agency reported that $58\%$ of people who had coronary bypass surgery in $2008$ were over the age of $65.$ Fifteen coronary bypass patients are sampled. Round the answers to four decimal places.

Part $1$ of $4$

$($a$)$ What is the probability that exactly $10$ of them are over the age of $65?$

The probability that exactly $10$ of them are over the age of $65$ is $\_\_\_\_\_$

Part $2$ of $4$

$($b$)$ What is the probability that more than $11$ are over the age of $65?$

The probability that more than $11$ are over the age of $65$ is $\_\_\_\_\_\_\_$

C$.$ What is the probability that fewer than $8$ are over the age of $65?$

$\_\_\_\_\_\_\_\_$

D$.$ Would it be unusual if all of them were over the age of $65?$ Yes or no