Find the critical z-value(s) for a left-tailed test of hypothesis for a proportion, with a sample size of 51 and a significance level of 0.5%. Find the critical z-value(s) for a right-tailed hypothesis for a mean, assuming the population standard deviation is known, with a sample size 75 and a significance level of 0.05%. Find the critical z-value(s) for a two-tailed test of hypothesis for a proportion, with a sample size of 102 and let a=0.02