3. A health insurance company would like to estimate the average waiting time for a b) patient seeking emergency room services. A random sample of 125 emergency room patients had an average waiting time of 218 minutes with a sample standard deviation of 72 minutes. (5 marks) Briefly explain why the t distribution should be used for developing the confidence interval for the population average in this case. (1 mark) Estimate the actual average with 90% confidence. Interpret this interval in the context of the question. Use Excel to find the critical value. (4 marks)