High blood pressure: A national survey reported that $31\%$ of adults in a certain country have hypertension $($high blood pressure$).$ A sample of $21$ adults is studied. Round the answer to at least four decimal places.

Part $1$ of $4$

What is the probability that exactly $6$ of them have hypertension? The probability that exactly $6$ of them have hypertension is $\_\_\_\_$

Part $2$ of $4$

What is the probability that more than $6$ have hypertension?The probability that more than $6$ have hypertension is $\_\_\_\_\_$

Part $3$ of $4$

What is the probability that fewer than $3$ have hypertension? $\_\_\_\_\_\_\_$

Part $4$ of $4$

Would it be unusual if more than $8$ of them have hypertension?

It $($would or wouldn't$)$ be unusual if more than $8$ of them have hypertension since the probability is $\_\_\_\_\_$