Seven randomly selected plants that bottle the same beverage implemented a time management program in hopes of improving productivity. The average time, in minutes, that it took the companies to produce the same quantity of bottles before and after the program are as follows:

75	89	31	90	120	50	40
70	80	30	85	100	49	42

Assume the two population distributions are normal.Construct a 90% confidence interval for_d. Assume that the paired data came from a population that is normally distributed.

Answer A (0.21, 10.93)

Answer B (1.60, 9.54)

Answer C (-0.22, 11.36)

Answer D (-22, 33.3)