p = 388/600 = 0.6467
b) Z for 99% confidence interval = Z0.005 = 2.575
Margin of error = Z0.005 * sqrt(p * (1 - p) / n)
                      Â
= 2.575 * sqrt(0.6467 * (1 - 0.6467) / 600)
                      Â
= 0.0502
a) Confidence interval = p + margin of error
                                  Â
= 0.6467 +
0.0502
                                  Â
= 0.5965 < p < 0.6969