Aresearcher wonders if there an association between the incidence of colds and the amount of vitamin c taken. he recruits 88 volunteers and randomly assigns 31 of them to take 500 mg of vitamin c, 15 of them to take 1000 mg of vitamin c and the rest to take no vitamin c. at the end of the study, it was determined that 28 of the volunteers did not have any colds where 18 of them were in the 500 mg group and 5 of them were in the 1000 mg group. test the appropriate hypothesis at α = .05 .