ExamW07

ExamW07 - For questions 1 20, circle one answer only. If...

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For questions 1 — 20, circle one answer only. If making an error, write your ±nal answer clearly in the margin. Ambiguous responses will be considered incorrect. 1. The mean age of ±ve people in a room is 30 years. One of the people whose age is 50, leaves the room. The mean age of the remaining people is 25 years. T F 2. For a Normal distribution, the upper and lower quartiles are respec- tively one standard deviation above and below the mean. T F 3. A correlation coe²cient based on a scatter plot measures the proportion of data lying on the regression line. T F 4. A phone—in poll at a radio station concluded that 70% of Canadians approve of Stephen Harper, based on the responses of 8,000 callers. The conclusion is valid since the sample size is large. T F 5. The weights of a type of tomato are believed to have standard deviation of 28g. If two such tomatoes are weighed together, their combined weight would have standard deviation 56g. T F 6. A random sample of 100 students are asked if they are vegetarians. Five percent respond yes, and a 99% con±dence interval for the true proportion of students who are vegetarians is found to be (0 . 03 , 0 . 07) . This implies 99% of all random samples of 100 students will have a sample proportion that falls between 0.03 and 0.07. T F 1
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7. Confdence intervals are constructed For both parameters and statistics. T ± 8. You carry out a hypothesis test that compares the means oF two popu- lations. Suppose a p-value oF 0.12 is obtained. This implies that there is a 12% chance that the two population means are equal. T ± 9. In linear regression, at a fxed value oF the explanatory variable, a 95% prediction interval For an observation oF the response variable is always wider than a 95% confdence interval For the mean response. T ± 10. One-way ANOVA provides evidence against the null hypothesis that the population means are all equal when the between-group variation is large compared to the within-group variation. T ± 11. IF the observations in a data set are all equal, then (a) the variance oF the data set equals 0. (b) the mean oF the data set equals 0. (c) the IQR oF the data set equals 0. (d) both (a) and (c). (e) both (b) and (c). 2
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12. The slope of a regression line and the correlation are similar in the sense that (a) they both have the same sign. (b) they do not depend on the units of measurement of the data. (c) they both fall between —1 and 1 inclusive. (d) neither of them can be aFected by outliers. (e) both can be used for prediction. 13. Which of the following is an incorrect statement about the correlation between two quantitative variables X and Y ? (a) A correlation of —0.8 indicates a stronger linear association between X and Y than a correlation of 0.5. (b)
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ExamW07 - For questions 1 20, circle one answer only. If...

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