This worksheet allows you to see how to compute critical z-values for confidence intervals. The middle section between the critical values is equal to the confidence level c and is bounded by the critical values. The shaded areas outside the middle section are equal to α = 1 - c, so each shaded area is equal to α/2.[br][br]This worksheet can also be used to find critical z-values for two-tail hypothesis tests.

What do the values in green always sum to?[br]As confidence level increases, what happens to the critical values?[br]As confidence level increases, what happens to the width of the confidence level?