Answer
a) -.8474< B1< -.5937
b) We are 95% confident that plant density is between .84 and .59 less than cob weight.
Work Step by Step
-Confidence Interval = B1 +- T(.025)SEB1
-T(.025) is found with DF= 19 to be 2.093 from table 4
-B1 = r(SDy/SDx). All three values are given so B1= (-.9418)(24.95/32.61) SO B1 = -.7206
-SEB1 = SDe/SDx(Radical of n-2). SDe is found to be 8.6, and n = 20 so plug in. SEB1 = .0606
-PLUG all these values into Confidence Interval formula to yield CI = -.7206 +- (2.093)(.0606) \
SO -.8474 < B1 < -.5937
