The narrower the confidence interval, the more precise it is. Which combination of factors will produce the most precise estimate of the difference between two population means?   a. two samples of n = 20 and 90% confidence   b. two samples of n = 50 and 80% confidence   c. two samples of n = 50 and 90% confidence   d. two samples of n = 20 and 80% confidence

5B. For part B, construct 90% and 95% confidence intervals for the population proportion. Interpret the results and compare the widths of the confidence intervals. b2. In a survey of 2241 U.S. adults in a recent year, 650 made a New Year's resolution to eat healthier.  5C. For part C, construct a 99% confidence interval for the population proportion. Interpret the results.  c1. In a survey of 1000 U.S. adults, 700 think police officers should be required to wear body cameras while on duty.  c2. In a survey of 600 United Kingdom teachers, 226 say they would wear a body camera in school.  5d. You wish to estimate, with 95% confidence, the population proportion of U.S. adults who think congress is doing a good or excellent job. Your estimate must be accurate within 4% of the population proportion.  d1. No preliminary estimate is available. Find the minimum sample size needed.  d2. Find the minimum sample size needed, using a prior survey that found that 25% of U.S. adults think congress…

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Siblings Mary and David are each attempting to estimate the proportion of families in their neighborhood who have five or more children. Mary selects a random sample of 50 families to survey, and she observes a sample proportion of 0.10. David selects a random sample of 100 families to survey, and he also observes a sample proportion of 0.10. Mary and David each use their sample data to construct a 95% confidence interval. Who will have the more narrow confidence interval? A. Both intervals will have the same width since the sample proportions are the same. B. Both intervals will have the same width since the level of confidence is the same for each interval. C. Both intervals will have the same width since the sample proportions are the same and the level of confidence is the same for each interval. D. Mary's interval will be more narrow than David's interval. E. David's interval will be more narrow than Mary's interval.

If you want to be confident in your estimation of a confidence interval, you should use….

9 The standard error of the mean is, a 0.881       b 0.735       c 0.612       d 0.510

If the analyst decides to increase the sample size (n) from 75 to 100, while maintaining the same confidence level, the width of the confidence interval would then: fluctuate up and down. remain unchanged. decrease. increase.

Construct the indicated confidence interval for the difference in proportions. Assume that the samples are Independent and that they have been randomly selected. A survey of randomly chosen adults found that 45% of the 231 women and 61% of the 275 men follow regular exercise programs. Construct a 95% confidence interval for the difference in the proportions of women and men who have regular exercise programs. O A. (-0.165, -0.155) OB. (0.052, 0.268 ) OC. (-0.246, -0.074) O D. (-0.267, -0.053) O E. (-0.250, -0.070 )

Days before a presidential election, an article based on a nationwide random sample of registered voters reported the following statistic, "52% (±3%) of registered voters will vote for Robert Smith." What is the "±3%" called? The "±3%" is called the confidence interval for a proportion. margin of error. sample proportion. standard error.