The body temperature of patients suffering from a kind of virus is normally distributed with unknown population mean and standard deviation of 0.4 degree Celsius. A sample of 20 such patients is selected for investigation,
and the sample mean is 38.5 degree Celsius.
(a) Find a point estimate of the population mean body temperature of the patients.
(b) Calculate the sampling error at 90% confidence.
(c) Construct a 90% confidence interval estimate of the population mean body temperature of the patients.