Renuka$$ Jain's Car Wash takes a constant time of $4$ minutes in its automated car wash cycle. Autos arrive following a Poisson distribution at the rate of $9$ per hour. Renuka wants to$$ know:

Part $2$

$$a$)$ The average wait time in the line $=$

$$

enter your response here minutes $($round your response to two decimal$$ places$).$

Part $3$

$$b$)$ The average number of customers waiting in the line $=$

$$

enter your response here cars $($round your response to two decimal$$ places$).$