A survey of 25 randomly selected customers found the ages shown (in years). The mean is 31.76 years and the standard deviation is 10.29 years. 21 20 30 14 450 a) How many degrees of freedom does the t-statistic have? 36 30 20 28 36 b) How many degrees of freedom would the t-statistic have if the sample size had been 400? 38 21 32 31 41 32 27 34 25 11 43 44 48 39