A Test of Writing Ability Is Given to a Random

Multiple Choice

A test of writing ability is given to a random sample of students before and after they completed a formal writing course.The results are given below.Construct a 99% confidence interval for the mean difference between the before and after scores if
(before-after) = 2.0 and
=2.6457

A) (-0.2,4.2)
B) (-0.1,4.1)
C) (-13.6,17.6)
D) (1.2,2.8)
E) (-0.5,4.5)