Find the critical value z using the standard normal distribution table, given a 90% confidence level. Please show a very detailed yet brief step by step solution. I will rate it helpful.

Finding Critical Values. Find the critical value za/2 that corresponds to the given confidence level. 90%

1. A sample size of n=15 is a simple random sample selected from a normally distributed population. Using Table C, find the critical value t* corresponding to a 95% confidence level in the following scenarios:

a.............to construct a confidence interval 

b..............one-sided hypothesis test 

c..............two-sided hypothesis test