Suppose a sample of 49 paired differences that have been randomly selected from a normally distributed population of paired differences yields a sample mean of d⎯⎯=4.2 and a sample standard deviation of sd = 7.6. (a) calculate a 95 percent confidence interval for µd = µ1 – µ2. can we be 95 percent confident that the difference between µ1 and µ2 is greater than 0?