We want to test the hypothesis that the mean quality characteristic of two dierent popula- tions are equal. The alternative hypothesis is that the means are not equal. The variances of the two populations are 4 and 6 respectively. We pick a sample of size 30 from the rst population and a sample of size 36 from the second. (a) What reference distribution would you use to test the hypothesis? [2 points] (b) If the sample mean from the rst population is 120 and that from the second pop- ulation is 121, what is the highest condence level at which you can reject the null hypothesis?