Fabrics respond differently to the same dye. Clothing manufacturers need to be able to match the colors of different fabrics. A researcher dyed samples of cotton and of ramie with a dye called procion blue, applied in the same way to each sample. Then she measured the lightness of the color with a colorimeter on a scale in which black is 0, white is 100. Here are the data for 8 pieces of each fabric.

Cotton:	48.82	48.88	48.98	49.04	48.68	49.34	48.75	49.12
Ramie:	41.72	41.83	42.05	41.44	41.27	42.27	41.12	41.49

Evidently one procedure gives darker colors than the other. Make a confidence interval estimate for the mean darkness of cotton minus the mean darkness of ramie after this dye procedure. Use 99% as your confidence level.

Lower Confidence Level:

Upper Confidence Level: