15.Which of the following statements about small-sample and large-sample confidence intervals for proportions p are true? I. The large-sample confidence interval formula for proportions is valid if np≥5 and n(1-p)≥5. II. Large-sample confidence intervals always contain the true parameter value, whereas small-sample confidence intervals may not. III. We form small-sample confidence intervals by using the large-sample formula after adding 4 successes and 4 failures. (A)I only (B)II only (C)III only (D)I and III only (E)I, II, and III

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.

相關試題

相關試卷