Question

O CONFIDENCE INTERVALS AND HYPOTHESIS TESTING Confidence interval for the difference of population means: Use ... A light bulb manufacturer wants to compare the mean lifetimes of two of its light bulbs, model A and model B. Independent random samples of the two models were taken. Analysis of 10 bulbs of model A showed a mean lifetime of 1240 hours and a standard deviation of 89 hours. Analysis of 14 bulbs of model B showed a mean lifetime of 1253 hours and a standard deviation of 95 hours. Assume that the populations of lifetimes for each model are normally distributed and that the variances of these populations are equal. Construct a 95% confidence interval for the difference H, H2 between the mean lifetime , of model A bulbs and the mean lifetime 4, of model B bulbs. Then complete the table below. Carry your intermediate computations to at least three decimal places. Round your responses to at least two decimal places. (If necessary, consult a list of formulas.) What is the lower limit of the 95% confidence interval? What is the upper limit of the 95% confidence interval? x 5 ?

Answer 1

- USW 85736364 solution Here ni=10, 1 =12uo, & 1789 2=14, T2 =1253, B2=95 so = (ni-D 84+ (M2-D 8 nitna-2 Se = 55% Cohit trem = 38-337 def=nit n2-2=1014-2=22 At asy, tal = 2.074 The asy.c-I for eally is G1-42) I talast = (1200-1253) + 2.074 (38.337) = -13 + 79.54 =(-92-511, 86-511) Lower limet - 92.511. upper limit = 66.511