The mean gross annual incomes of certified tack welders are normally distributed with the mean of $50,000 and a standard deviation of $4,000. 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 -1.96 and 1.96; otherwise, reject it.
b. do not reject the null hypothesis if computed z lies between -1.65 and 1.65; otherwise, reject it.
c. do not reject the null hypothesis if computed z is greater than 1.65; otherwise, reject it.
d. reject the null hypothesis if computed z is below -1.96; otherwise, reject it.