Steven is conducting a two-tailed z-test with an alpha level of .01. His population mean is 100, and his population standard deviation is 15. The sample mean is 115 with an n of 30.

What is his standard error of the mean (error margin = 0.1)?

What is the absolute value of his z observed(error margin = 0.1)?

What is the absolute value of his critical values (error margin = 0.02)?