The mean amount purchased by a typical customer at Churchill's Grocery Store is $27.50 with a standard deviation of $7.00. Assume the distribution of amounts purchased follows the normal distribution. For a sample of 68 customers, answer the following questions. a. What is the likelihood the sample mean is at least $30.00? (Round z value to 2 decimal places and final answer to 4 decimal places.) Probability b. What is the likelihood the sample mean is greater than $26.50 but less than $30.00? (Round z value to 2 decimal places and final answer to 4 decimal places.) Probability c. Within what limits will 90 percent of the sample means occur? (Round your answers to 2 decimal places.) Sample mean and