a . The test statistic is -1.160740861
b. The p value is 0.2457473
Let the point estimate be 'a'. The formula for test statistic is:
Z = (a - p) / √ { [ p×(1-p) ]÷n }
Point Estimate 'a' = 30/78 = 0.384615385
Z = (0.384615385 -0.45 ) / √[ (0.45 × 0.55) ] / 78
Z = -0.065384615 / 0.056330071
Z = -1.160740861