help me please

Complete parts (a) through (c) below (a) determine the critical value(s) for a right - tailed test of a population mean at the oc = b.01.level of significance with 20 degrees of freedom. (b) determine the critical valuela ) for a left - tailed fast of a population mean at the ac - 0.05 level of Significance based on a sample size of n =15. (C) determine the critical valueli) for a tong. tailed test of population mean at the a = 0.01 lived of significance based on a sample size of n=19 (@) tarit = - ( Round to 3 decimalplaces asneeded) ( b)+critz ( c) tcritz