According to an IRS study, it takes a mean of 330 minutes for taxpayers to prepare, copy, and electronically file a 1040 tax form. This distribution of times follows the normal distribution and the standard deviation is 80 minutes. A consumer watchdog agency selects a random sample of 40 taxpayers.
a. What is the standard error of the mean in this example? (Round your answer to 3 decimal places.)
b. What is the likelihood the sample mean is greater than 320 minutes? (Round z value to 2 decimal places and final answer to 4 decimal places.)
c. What is the likelihood the sample mean is between 320 and 350 minutes? (Round z value to 2 decimal places and final answer to 4 decimal places.)
d. What is the likelihood the sample mean is greater than 350 minutes? (Round z value to 2 decimal places and final answer to 4 decimal places.)