Hi Guys, I need help with reading Z tables for probablity questions. To my understanding the significance level is (1-Confidence Level). The value i obtain from the Z table end up being incorrect. Also the sheer volume of the formulas is making it hard to memorise all of them. Any tips on memorising formulas are welcome.
For example in the Hypothesis Testing reading it says: a 5% significance level (alpha = 0.05) for a two tailed test is compared against critical z-values of ± 1.96. The values ± 1.96 correspond to ± z (alpha/2) = ± z0.025. I understand that the significance level must be divided by two for the range values for a two tailed test. I don’t understand how ±z0.025 translates to ±1.96 by looking up the z-table. Likewise how does -z0.05 for a one tailed test translate to a z-value of -1.645?