First we find the z-score for this confidence interval: Convert 95% to a decimal: 95/100 = 0.95 Subtract from 1: 1 - 0.95 = 0.05 Divide by 2: 0.05/2 = 0.025 Subtract from 1: 1 = 0.025 = 0.975
Using a z-table (http://www.z-table.com) we look up this value in the chart; the z-score that goes with this value is 1.96.