A manufacturer of furniture claims that the company's new model of bookshelves is easier to assemble than the old model. To test the claim, 7 people were assigned to assemble bookshelves from each of the two models. Here are the times (in minutes) they needed to assemble the bookshelves. Person
1 2 3 4 5 6 7
Old model 17 22 20 14 15 21 24
New model 15 19 18 13 15 19 23
A) Construct a 95% confidence interval for the differences.
B) Test if the mean assembly time for the new model is shorter than that of the old model using a = 0.05.
C) Now consider the data as two independent samples and conduct the test as a two sample test. Assume equal variances. Is the decision reversed?