Sol Tutorial 7

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Unformatted text preview: ation distribution is right‐skewed. However the sampling distribution will be roughly normal as the sample size is large (more than 30). d. Even if the normality assumption is not met, the analysis is still likely to produce valid results. ST1131 Introduction to Statistics Tutorial 7 s = 100, n = 400, ME = t(SE) (i) For 95% CI, the ME = 1.98 (100/√400) = 9.9 (ii) For 99% CI, the ME = 2.617(100/√400) = 13.085 ME= $1000, Z = 2.58, For a roughly normal distribution, s ≈ range /6 = $120,000/6 = $20,000 n = (Zs/ME) = (2.58 * 20,000/1,000) = 2662.56 = 2663 The margin of error increases when the confidence level is higher. ME = 0.05, Z = 1.96 a. b. c. p = 0.5 n = p(1‐p)(Z/ME)2 = 0.5*0.5 (1.96/0.05) 2 = 384.16 = 385 p = 0.19 n = p(1‐p)(Z/ME)2 = 0.19*0.81 (1.96/0.05) 2 = 236.49 = 237 it overestimates the sample size a lot. It would be more costly than needed. 3...
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This document was uploaded on 03/13/2014.

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