In a single phase single server service process where both interarrival time and service times are exponentially distributed, it can be assumed that the total time that a customer spends in the process is also exponentially distributed. Suppose the total time the customers spend in a pharmacy is exponentially distributed with mean of 5 minutes. The pharmacy has promised to fill all prescriptions in 11 minutes.

1. What percentage of the customers cannot be served within this time limit?

The potential answers are:

A: 11.08%

B: 9.7%

C: 8.21%

D: 4.98%

E: 13.53%

2. 89% of customers are served in less than what time interval?

The potential answers are:

A: 4.24 minutes.

B: 4.61 minutes.

C: 6.36 minutes.

D: 11.04 minutes.

E: 12.72 minutes.

3. What is the probability of arrival of exactly 5 customers in 15 minutes.

The potential answers are:

A: 9.02%

B: 27.07%

C: 10.08%

D: 22.4%

E: 19.54%

4. What is the probability of arrival of at most 5 customers in 15 minutes.

The potential answers are:

A: 91.61%

B: 64.72%

C: 94.73%

D: 67.67%

E: 98.34%