Solutions HWA7

13.4a: 95% of the hand luggage weight 25 +/- (1.96)(5) lbs. Or 95% of the luggage weigh in the interval [15.2,34.8]. This is a statement about the population. This question could have been asked in Chapter 8.

13.4b: 95% C.I.: mu = 25 +/- (1.96)(5/sqrt[225]) = [24.35, 25.65]

Or 95% C.I.: 24.35 <= mu <= 25.65. This is an estimate of the parameter mu.

13.4c: 99% C.I.: mu = 25 +/- (2.576)(5/sqrt[225]) = [24.14, 25.86]

Or 99% C.I.: 24.14 <= mu <= 25.86. This interval estimate of the parameter mu is wider than the 95% C.I. because we trade accuracy for confidence.

13.8a: 95% C.I.: mu = 195230 +/- (1.96)(63125/sqrt[50]) = 195230 +/- 17497.36 = [177732.64, 212727.36]

Or 95% C.I.: $177,732.64 <= mu <= $212,727.36.

13.8b: 95% C.I.: mu >= 195230 – (1.6448) (63125/sqrt[50]) = 180546.50

13.14a: Here x-bar = 24, s = 1.8708, n = 5, df = 4.

90% C.I.: mu = 24 +/- (2.1318)(1.8708/sqrt[5]) = 24 +/- 1.7836 = [22.2164,25.1784]

13.14b: 95% C.I.: mu >= 24 – (2.1318)(1.8708/sqrt[5]) = 22.2164