Question

To compare two kinds of bumper guards, 6 of each kind were mounted on a certain kind of compact car. Then each car was run into a concrete wall at 5 miles per hour, and the following are the costs of the repairs for the two samples in dollars. Bumper guard 1 shows a sample mean of 127.95 , and a variance of 584 , while bumper guard 2 shows a sample mean of 130.4, and a variance 216 Assume the two populations are normally distributed with unknown and unequal variances. Then a 0.9 confidence interval for the difference between the two population means has the lower limit  , and an upper limit equals to

Answer 1