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 = 2.1	mean = 2.9
standard deviation = 0.8	standard deviation = 1.7
sample size = 100	sample size = 100

Find a 90% confidence interval for the mean difference between the shelf life of the two brands of doughnuts.

(-1.109, -0.491)

(-1.111, -0.4889)

(-1.171, -0.4286)

(-1.11, -0.4895)

(0.83037, 1.5696)