The waiting time to get food at a fast-food restaurant is 5.1 minutes on average with standard deviation of 2.1 munutes. Suppose that a sample of 39 customers is randomly selected. A. What are the mean and standard deviation of the sample mean waiting time of 39 customers? Mean = minutes Standard Deviation (standard error of the mean) minutes Round standard error to 5 decimal places. B. What is the probability that the average waiting time of 39 customers is less than 4.9 minutes? Answer: Round to 4 decimal places. C. What is the probability that the average waiting time of 39 customers is greater than 5.3 minutes? Answer: Round to 4 decimal places. D. What is the probability that the average waiting time of 39 customers is between 4.9 and 5.3 minutes? Answer: Round to 4 decimal places. E. Why were we able to use the normal model in this case? Choose an appropriate explanation below. Because the sample size is small, and we know that for small enough samples, the distribution of the sample mean is approximately normal. Because the distribution of the waiting time of customers at a fast food restaurant is normal. Because the distribution of the sample mean is always normal, regardless of the sample size. Because the sample size is large, and we know that for large enough samples, the distribution of the sample mean is approximately normal.