hw.prop.CI.Hypo.pVal.STS.KEY

Use 3 decimal places for the standard deviation 1 p1

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Unformatted text preview: ormula with symbols only. Show work. Use 3 decimal places for the standard deviation. ^ (1 - ^) p(1 - p) p p ⎛ 0.64(0.36) ⎞ KEY: ^ ± Z* p but must use ^ ± Z* p 0.64 ± 1.96*⎜ = 0.096⎟ n n 25 ⎝ ⎠ [0.45, 0.83] 6f. State the interpretation of the CI. KEY: We are 95% Confident that the unknown population proportion p is in the interval [0.45, 0.83] 6g. Suppose our null hypothesis is Ho: p ≥ 0.55 . Compute the p-value. Show all work including the raw formula with symbols (no numbers). No credit unless proper subscripts are used everywhere. Use 3 decimal places for the standard deviation. ^ sample - p p 0.64 - 0.55 0.09 = = = 0.91 Zsample = 0.099 p(1- p) 0.55(0.45) n 25 Area for Z = 0.91 is 0.3186. p-value is on the same side as alpha – it has the same "tail" as alpha. Thus, the p-value = 0.5000 + 0.3186 = 0.8186 6h. 7. 7a. What is the decision based on this p-value? KEY: can't reject, since the p-value is so large We'll test at α = 0.01 whether the population proportion of airline passengers checking baggage is at least 0.55 . A sample of 25 passengers showed 9 checked their baggage. Determine whether it is OK to use the Normal distribution for this problem. KEY: OK to use Z if np>5 and n(1-p)>5: 25(0.55)=13.75 > 5, 25(0.45)=11.25 > 5 so OK to use Z 7b. Hypothesis testing using the regular method: Show all work including the raw formula with symbols (no numbers). No credit unless proper subscripts are used everywhere. Use 3 decimal places for the standard deviation. Draw a graph and fill it out completely. 1. State Hypotheses KEY: Ho p ≥ 0.55 H1...
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This note was uploaded on 01/27/2013 for the course STAT 385 taught by Professor Szatrowski during the Spring '08 term at Rutgers.

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