23.Let (Yᵢ, xᵢ), i=1,2,...,n, be a random sample. (A)Since the sample correlation coefficient is found to be r=0.9, simple linear regression model would be suitable for modelling the relationship for Y and x. (B)It is further known that both the sample standard deviations of Y and x are 1's, then the estimated regression coefficient would be 0.9. (C)Normal distribution assumption is a must for the error term if we want to find the least squares estimate. (D)A significant result can be obtained if r=0.9, because the value is large enough. (E)None of the above.

5.What is meant by the term "90% confident" when constructing a confidence interval for a mean? (A)If we took repeated samples, approximately 90% of the samples would produce the same confidence interval. (B)If we took repeated samples, approximately 90% of the confidence intervals calculated from those samples would contain the sample mean. (C)If we took repeated samples, approximately 90% of the confidence intervals calculated from those samples would contain the true value of the population mean. (D)If we took repeated samples, the sample mean would equal the population mean in approximately 90% of the samples. (E)We are 90% confident that 90% of the data falls within the confidence interval.

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