Diana wants to know the true mean height of NC States's seasonal poinsettias. She has been working in the green house for a few years and notices they have very little variation.

Her boss advises her to take as many samples as possible from different areas in the green house. Diana takes 50 samples out of the more than the 200 plants grown. She finds that the average height of the plant is 18 inches with a standard deviation of 4 inches (proabably because they come from one parent plant).

Diana wants to construct a 95% Confidence Interval of the heights of NC Sates's poinsettias. Find the lower and upper bounds of Diana's confidence interval.