Jason sampled 60 smokers who were questioned about the number of hours they sleep each day. Jason wants to test the hypothesis that the smokers need less sleep than the general public which needs an average of 7.5 hours of sleep with a population standard deviation of 0.7 hours. z equals fraction numerator x with bar on top minus mu over denominator begin display style fraction numerator sigma over denominator square root of n end fraction end style end fraction If the sample mean is 7.2 hours, what is the z-score