Consider a sample with 10 observations of 3 8 4 2 4 15 6 0 4

Consider a sample with 10 observations of -3, 8, 4, 2, -4, 15, 6, 0, -4, and 5. Use z scores to determine if there are any outliers in the data; assume a bell-shaped distribution. Now the answer in the book says The z-scores for the smallest and largest observations are z= - 1.04 and z = 2.01 respectively, hence, not outliers.. I have done this many times and am not getting the same answer.