You wish to test the foll problem. Po = 12 first rese data represents a post-test You believe the population of difference scores is normally distributed, but you do not know the standard deviation. You obtain the following sample of data: pre-test post-test 54.6 54.2 34.7 59.2 61.1 29.2 247 59.6 57.2 39.1 32 56 55.7 73.4 67.6 59.6 44.9 60.8 56.6 673 60.4 23.9 44.9 76.4 42.4 45.6 45 44.4 29.2 175 37.4 38 415 43