The 95% confidence interval for a certain proportion p is from 0.23 to 0.63. We conducted a hypothesis test for p. The null hypothesis is H0:p=a . The alternative hypothesis is Ha:p≠a. What is the mean for the all possible values of a which would not be rejected as plausible values of the population proportion at a 5% significance level? The mean for the all possible values of a which would not be rejected as plausible values of the population proportion at a 5% significance level is .