A random sample of 18 observations produced a sample mean of 9.24. Find the critical and observed

Question:

A random sample of 18 observations produced a sample mean of 9.24. Find the critical and observed values of z for each of the following tests of hypothesis using .05. The population standard deviation is known to be 5.40 and the population is normal.
a. H0: µ = 8.5 versus H1: µ ≠ 8.5
b. H0: µ = 8.5 versus H1: µ > 8.5
Distribution
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