Suppose feature movie lengths (in hours) were measured for all movies shown in 2017 in the U.S. The mean length of all feature length movies shown was 1.80 hours with a standard deviation of 0.15 hours. Suppose the length of a random sample of 20 movies was recorded from all movies released in 2017. The mean length of the feature length movies was found to be 1.72 hours with a standard deviation of 0.18 hours.
Suppose the process of taking random samples of size 20 is repeated 200 times and a histogram of the 200 sample means is created. The histogram would be a display of which of the following?