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Unformatted text preview: .6745. b. Q1 = µ +Zσ = 100 + (‐0.6745)(16) = 89.2 Q1 = µ +Zσ = 100 + (0.6745)(16) = 110.8 25% of MDI is below 89.2 while 25% of MDI is above 110.8 c. IQR = 110.8 – 89.2 = 21.6 d. Q1‐1.5IQR = 89.2 – 1.5(21.6) = 56.8 Q3+1.5IQR = 110.8 + 1.5(21.6) = 143.2 MDI scores lower than 56.8 or higher than 143.2 would be considered as outliers. 2 ST1131 Introduction to Statistics Tutorial 6 a. Standard error when n is 100 = √p(1‐p)/n = √(0.5*0.5/100) = 0.05 Standard error when n is 1000 = √p(1‐p)/n = √(0.5*0.5/1000) = 0.016 a. b. c. d. b. The sample proportion is likely to fall within 3 standard errors of the mean. In (i) mean = 0.5, SE= 0.05, this would be between 0.35 to 0.65. In (ii) mean = 0.5, SE = 0.016, this would be between 0.45 to 0.55. 3 c. SE is smaller when n is larger (A larger sample is more accurate than a smaller sample). Thus the interval of 3 SE of the mean from a larger sample will be shorter (more precise estimate) than a smaller sample. Let x = 1 if a female is selecte...
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This document was uploaded on 03/13/2014.

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