a company claims a new ointment speeds healing. to test the claim a researcher conducts an experiment involving 30 participants who have recently suffered a minor cut or scrap. half the group uses the ointment twice daily the other group does not. the cuts treated with the ointment took a mean 4.6 days to heal with sd 1.3 days. the other group mean 6.1 days n sd of 1.6 days. test the company's claim at .01 level of significance. assuming population variance are not equal