Find the critical value of the sample mean for the given sit

Find the critical value of the sample mean for the given situation:

H0: more or equal to 400

H1: < 400

alfa= 0.01,

n = 63

= 18

(Round your answer(s) to 2 decimal places.)

Critical value of =

The Critical value of at 0.01 level of significance is given by Z = -2.33( from standard normal tables)