A study found the average time for taxpayers to prepare and file their daily income tax return is 330 minutes, with a standard deviation of 80 minutes. A random sample of 40 taxpayers was taken. The standard error of the sample mean is 80/sqrt(40) = 12.5 minutes. There is a 50% likelihood the sample mean is greater than 320 minutes. There is a 68% likelihood the sample mean is between 320 and 350 minutes.