The Mean Annual Incomes of Certified Welders Are Normally Distributed

Multiple Choice

The mean annual incomes of certified welders are normally distributed with the mean of $50,000 and a 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 critical value?

A) +1.645
B) -1.282
C) ±1.282
D) ±1.645