# Standard deviation standard error n p p 1 n p p p p z

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standard deviation (standard error)npp)1(nppppZ)1(ParameterSituationConfidenceInterval forParameterCommentσ knownX normallydistributed or n≥ 30nzxFor z use the value z* such thatP(-z* < Z < z*) = confidence coefficient.Itis rare to knowwhen you don’t know.unknownX normally distrib-utedorn30nstxReference the t-distribution with n-1degrees of freedom.For t use the valuet* such thatP(-t* < t < t*) = confidencecoefficient.nsis an estimate ofn.pnp5 and n(1-p)5(i.e.,npn515)nppzp)1(For z use the value z* such thatP(-z* < Z < z*) = confidence coefficient.npp)1(is an estimate ofnpp)1(.Parameter forwhich confidenceinterval soughtSample size to achieve pre-setconfidence level and margin of error(E) targetsComment
222)(EofestimateznIf calculated n is < 30, actuallysample 30.If X is estimated torange from L to H, may use4LHas estimate of σ.p22)1)((EpofestimatepofestimateznIf no estimate of p is available,substitute .50 forestimate of p.Practice Problems for Test #3For all hypothesis testing problems, use the p-value approach.Chapter 9 Hypothesis Testing8.Out of a random sample of 150 employees of a large company, 22 indicated that theyplanned to take an early retirement.Does this sample suggest that more than 10% of all thecompany's employees plan to take an early retirement?Would a person desiring to use asignificance level of .01 reject the null hypothesis?Chapter 11 Chi-Square Test of Independence9.A financial consultant wishes to determine whether, for firms in a given industry, there is arelationship between firm asset size and capital structure.A random sample of 134 firms inthe industry was selected, and cross-classified as follows:firm asset sizecapital structurelowmediumhighdebt less than or = equity142016debt greater than equity303618Does this sample data provide evidence to conclude that firm asset size and capitalstructure are related?Chapter 9 Hypothesis Testing10. A mail order company’s standard shipping fee is based on the assumption of a mean packageweight of 20 ounces.A random sample of 40 packages sent out recently had a mean weight of21.3 ounces with a standard deviation of 3.7 ounces.Does this sample suggest that the meanweight of the packages sent out by this company is not 20 ounces?Would a person desiring touse a significance level of .10 reject the null hypothesis?Chapter 3 Correlation Coefficient

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Term
Spring
Professor
DODONOVA