Please provide answer the question to the fourth decimal place.  I am just checking my answer...  I completed the answers for A and B below, which you need to solve C.

Do social shoppers differ from other online consumers with respect to spending behavior? A study of browser-based shopping sessions reported that social shoppers, consumers who click away from social networks to retail sites or share an item on social network, spent a mean of 126.12 on a retail site in a 30-day period compared to other online shoppers who spent a mean of $115.55. (Data extracted from "Social shoppers spend 8% more than other online consumers," bit.ly/1FyyXP5.) Suppose that the study consisted of 500 social shoppers and 500 other online shoppers and the standard deviation of the order value was $40 for social shoppers and $10 for other online shoppers. Assume a level of significance of 0.05.

a) Is there evidence of a difference in the variances of the order values between social shoppers and other online shoppers? Yes.  I used a upper-tail f-test for the difference of two variances.

b) Is there evidence of a difference in the mean order value between social shoppers and other online shoppers? Yes.  I used a separate variance t-test for the difference of two means.

c) Construct a 95% confidence interval estimate for the difference in mean order value between social shoppers and other online shoppers.