Question: The net average (mean) earnings of a certain type of medical specialist in the U.S. is $155,800 per year. Exactly 31 of these specialists reside in eastern Oregon and eastern Washington, earning the salaries listed below. You may assume the distribution of these net salaries nationwide is normal. Find the mean and the standard deviation of the salaries listed below. Use the 5% level of confidence to test the claim that the mean earnings of these 31 specialists are different from the national average. You may assume that the standard deviation of the data below matches the standard deviation of the nationwide data.

$ 93,700 2x
$110,500 2x
$123,300 3x
$129,900 3x
$136,800 4x
$140,200 5x
$142,700 5x
$153,400 3x
$173,600 2x
$184,200 2x