A grocery store is interested in determining whether or not a difference exists between the shelf life of two different brands of doughnuts. A random sample of 100 boxes of each brand was selected and the shelf life in days was determined for each box. The sample results are given below.

Brand A

Brand B

Mean (x-bar) = 2.1

Mean (x-bar) = 2.9

s = 0.8

s = 1.1

n = 100

n = 100

Find a 90% confidence interval for μA - μB, the difference in mean shelf life between brand A and brand B. Assume that the assumptions and conditions for inference have been met.