Question

Question 2 of 2 -/15 View Policies Current Attempt in Progress Arandom sample of 1500 residential telephones in Phoenix found that 380 of the numbers were unlisted. A random sample in the same year of 1200 telephones in Scottsdale found that 315 were unlisted. Round your answers to four decimal places (e.g.98.7654). (a) Calculate a 95% two-sided confidence interval on the difference in the proportions of unlisted numbers between the two cities. Sp1-p2s (b) Is there a significant difference between the two proportions at a = 0.05? (c) Calculate a 90% two-sided confidence interval on the difference in the proportions of unlisted numbers between the two cities. Sp1-p2s Statistical Tables and Charts e Textbook and Media Save for Later Attempts: 0 of 3 used Submit Answer

Answer 1

Q ginen Phoenix Scottsdale ni 1500 N₂ = 1200 X= 380 X2= 315 Pc = = 0.2533 ca EX2 0.2685 ا) at x=0.05 Zc c=1.96 [ for 95%. CI - for SE = x PC-f) . 7, e-f,) Pi-P2 ni nz = 1.96 x 0.25361-0.2933 0.263(1-0-2639 + 1500 1200 2003 0.0328 0.0328 951, CI for (Pi-P2) is (CP-82) I SE) (0.2533 – 0.2625) + 0.0328 1992 (-0.0092 £ 3 (-0.2420 , 0.0936 ) 95 H CI for Pi-P2 is -0.0420, 0.0236 since o ir lie in this internal We conclude that there is no significant difference at 220.05 live for 870.10 Les lobus [ for 90% CI for Po-P2 SE = Ze x Bico-e) + P2C! P.) ni ni n2 1.645 X 0.25336,-0.2533) + 0.262511-0.2625) 1500 (200

SE = 99 0.0275 90% CI for (P. -P₂) is (CPP) I SE) ( -0.0092 $ 0.0975 ) (-0.0367, 0.0183) 90-1 CI for Pilz is oo (-0.0367, 0.0183) و