20. The number of students using the ATM on campus daily is normally distributed with a mean of 237.6 and a standard deviation of 26.3. You take a random sample of 30 days. Find two values"a" and"b" that are symmetric around the mean such that the probability is 0.95 that the sample mean is greater than"a" and less than"b". a) These two equations imply that a = 228.189 and b = 247.01 b) These two equations imply that a = 237.6 and b = 247.01 c) These two equations imply that a = 263.9 and b = 211.3 d) These two equations imply that a = -1.96 and b = 1.96 e) None of the above