Determine the critical value(s) for a right-tailed test of a population mean at the alphaequals0.01 level of significance with 20 degrees of freedom. (b) determine the critical value(s) for a left-tailed test of a population mean at the alphaequals0.01 level of significance based on a sample size of nequals10. (c) determine the critical value(s) for a two-tailed test of a population mean at the alphaequals0.10 level of significance based on a sample size of nequals18