The population is normally distributed with a population standard deviation of 72

Consider the following hypotheses:

H0: μ = 260
HA: μ ≠ 260

The population is normally distributed with a population standard deviation of 72. 

a. Use a 1% level of significance to determine the critical value(s) of the test.
b-1. Calculate the value of the test statistic with formula x hat = 294 and n = 85. 
b-2. What is the conclusion at α = 0.01?
c. Use a 10% level of significance to determine the critical value(s) of the test.
d-1. Calculate the value of the test statistic with formula x hat = 238 and n = 85.
d-2. What is the conclusion at α = 0.10?