Answer: a) critical value = 0.0853, b) we reject the null hypothesis.
Explanation:
Since we have given that
z = -1.37
And the hypothesis are given below:

Since α = 0.01
since critical value = 0.0853
As we can see that 0.853 < 0.25.
so, we reject the null hypothesis.
Hence, a) critical value = 0.0853, b) we reject the null hypothesis.