{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

statistics for business and economics 11th edition chapter 7 - exercise solution

Statistics for business and economics 11th edition chapter 7 - exercise solution

This preview shows pages 1–3. Sign up to view the full content.

Chapter 7 Sampling and Sampling Distributions Solutions: 15. a. \$45,500 / \$4,550 10 i x x n = Σ = = b. 2 ( ) 9,068,620 \$1003.80 1 10 1 i x x s n Σ - = = = - - 16. a. We would use the sample proportion for the estimate. 5 .10 50 p = = (Authors' note: The actual proportion from New York is 52 .104. 500 p = = ) b. The sample proportion from Minnesota is 2 .04 50 p = = Our estimate of the number of Fortune 500 companies from New York is (.04)500 = 20. (Authors' note: The actual number from Minnesota is 18.) c. Fourteen of the 50 in the sample come from these 4 states. So 36 do not. 36 .72 50 p = = (Authors' note: The actual proportion from the other states is 366 .732. 500 p = = ) 18. a. E x ( ) = = μ 200 b. σ σ x n = = = / / 50 100 5 c. Normal with E ( x ) = 200 and σ x = 5 d. It shows the probability distribution of all possible sample means that can be observed with random samples of size 100. This distribution can be used to compute the probability that x is within a specified ± from μ . 19. a. The sampling distribution is normal with E ( ) x = μ = 200 / 50 / 100 5 x n σ σ = = = For ± 5, 195 205 x Using Standard Normal Probability Table: At x = 205, 5 1 5 x x z μ σ - = = = ( 1) P z = .8413 At x = 195, 5 1 5 x x z μ σ - - = = = - ( 1) P z < - = .1587 (195 205) P x = .8413 - .1587 = .6826 b. For ± 10, 190 210 x Using Standard Normal Probability Table: At x = 210, z x x = - = = μ σ 10 5 2 ( 2) P z = .9772 At x = 190, 10 2 5 x x z μ σ - - = = = - ( 2) P z < - = .0228 (190 210) P x = .9772 - .0228 = .9544

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Chapter 7 26. a. 939 / x z n σ - = Within ± 25 means x - 939 must be between -25 and +25. The z value for x - 939 = -25 is just the negative of the z value for x - 939 = 25. So we just show the computation of z for x - 939 = 25. n = 30 25 .56 245/ 30 z = = P (-.56 z .56) = .7123 - .2877 = .4246 n = 50 25 .72 245/ 50 z = = P (-.72 z .72) = .7642 - .2358 = .5284 n = 100 25 1.02 245/ 100 z = = P (-1.02 z 1.02) = .8461 - .1539 = .6922 n = 400 25 2.04 245/ 400 z = = P (-2.04 z 2.04) = .9793 - .0207 = .9586 b.
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}