Z TESTING AT n LESS THAN 30

#4
the question is in the first line
This depends on whether the test is one tailed or two.

For Null hypothesis H0: μ≥μ0 vs alternative hypothesis H1: μ<μ0 , it is upper/right-tailed (one tailed).

For Null hypothesis H0: μ≤μ0 vs alternative hypothesis H1: μ>μ0 , it is lower/left-tailed (one tailed).

For Null hypothesis H0: μ=μ0 vs alternative hypothesis H1: μ≠μ0 , it is two-tailed.

https://en.wikipedia.org/wiki/Z-test