Question

STEP 2 of 3: find the margin of error

A telephone service representative believes that the proportion of customers completely satisfied with their local telephone service is different between the Midwest and the Northeast. The representative's belief is based on the results of a survey. The survey included a random sample of 1120 midwestern residents and 1020 northeastern residents. 51 % of the midwestern residents and 55 % of the northeastern residents reported that they were completely satisfied with their local telephone service. Find the 99 % confidence interval for the difference in two proportions. Step 1 of 3 : Find the point estimate that should be used in constructing the confidence interval.

step 3 of 3: construct the confidence interval

Answer 1

A po 0.51 a 0.55 1 Ar 7 Solution Given na 1120 1020 Pe * At 99% Confidence interval is, Qe (-0.99 0.01 a 0.01 0.005 2 2 Z Z 2.576 0.005 Using etable Bry Maagim of esser. Ze game.) 22 (1-02) 7 2 n. nz 2.576 10.51(2-0.51), 0.55(1-0.55) 1120 1020 = 0.056 at Point estimate 0.51 0.55 2 -0.04 & The 99% Confidence interval is pôdf -0.04 0.056 CP, - PR -0.04 + 0.056 -0.096 L P P S 0.016