For items 19 - 22, conduct each hypothesis test indicated using either the z or t distribution, as appropriate. Note: S, =0, (the sample estimate of the population standard deviation) x = population standard deviation (12 points; 3 points each) 19. Ho: H = 50 Obtained value: Sx = 10 n = 20 Critical value: a = 0.05 X =54 Decision: (Reject or fail to reject the null hypothesis) 20. Ho: H = 50 Obtained value: Ox = 15 n = 70 Critical value: a = 0.05 X = 46 Decision: (Reject or fail to reject the null hypothesis) 21. Ho: M = 100 Obtained value: Sx = 21 n = 25 Critical value: a = 0.05 X - 97 Decision: (Reject or fail to reject the null hypothesis) 22. Ho: H = 0 Obtained value: 0-5 n = 60 Critical value: a = 0.10 X -2 Decision: (Reject or fail to reject the null hypothesis)