n The value for Po is the hypothesized population proportion we are testing for. Here, we have Po n = 160 Step 2 160 =0.85 0.85 There was a sample of 160 items given, so we have Now that all of the values have been identified, the test statistic can be calculated. Use p = 0.78, p = 0.85, and n = 160 to find the value of the z test statistic, rounding the result to two decimal places. Z= P-Po Po(1-Po) 0.78- n 0.85(1 -0.85) 160