Studies in the general population suggest that the gestational length of uncomplicated pregnancies vary according to a Normal distribution with mu=39 weeks and sigma=2 weeks. A sample of 28 babies born to teenagers demonstrates an average gestational length (x-bar) of 38.3 weeks. Test whether the mean gestation period in teenagers is significantly different from the expected value of 39 weeks. Use a two-sided alternative. Show all hypothesis testing steps