As part of a marketing study, the food king supermarket chain has randomly sampled 150 customers. the average dollar volume purchased by the customers in this sample was $31.14, that is , the sample mean from a sample of size 150 was $31.14. Before sampling, the company assumed that the population distribution of customer purchases had a mean of $30.00 and a standard deviation of $8.00. What is the probability of observing a sample mean of $31.14 or greater?