The Mean Annual Income of Certified Welders Is Normally Distributed

Multiple Choice

The mean annual income of certified welders is normally distributed with a mean of $50,000 and a population standard deviation of $2,000. The ship building association wishes to find out whether their welders earn more or less than $50,000 annually. The alternate hypothesis is that the mean is not $50,000. If the level of significance is 0.10,what is the decision rule?

A) Do not reject the null hypothesis if computed z lies between −1.645 and +1.645; otherwise,reject it.
B) Do not reject the null hypothesis if computed z is greater than 1.645; otherwise,reject it.
C) Do not reject the null hypothesis if computed z lies between −1.960 and +1.960; otherwise,reject it.
D) Reject the null hypothesis if computed z is below −1.960; otherwise,reject it.