A college has 250 full-time employees that are currently covered under the school's health care plan. The average out-of-pocket cost for the employees on the plan is $1,920 with a standard deviation of $510. The college is performing an audit of its health care plan and has randomly selected 30 employees to analyze their out-of-pocket costs. a. Calculate the standard error of the mean. b. What is the probability that the sample mean will be less than $1,875 ? c. What is the probability that the sample mean will be more than $1,890 ? d. What is the probability that the sample mean will be between $1,945 and $1,970 ? a. The standard error of the mean is (Round to two decimal places as needed.)