Statistical Inferences Answers

When finding the margin of error for the mean of a normally distributed population from a sample, what is the critical probability, assuming a confidence level of 86%?

Which of the following statements is correct?

A simple random sample of 90 is drawn from a normally distributed population, and the mean is found to be 138, with a standard deviation of 34. What is the 90% confidence interval for the population mean? Use the table below to help you answer the question.Confidence Level90%95%99%z*-score1.6451.962.58Remember, the margin of error, ME, can be determined using the formula .

A simple random sample is drawn from a normally distributed population. The value of which of the following will not be known for certain but can be inferred?

All else being equal, if you cut the sample size in half, how does this affect the margin of error when using the sample to make a statistical inference about the mean of the normally distributed population from which it was drawn?.

The number of sit-ups that all tenth-grade girls can do in 5 minutes is normally distributed. Beth surveyed 20 of her fellow intramural tennis players, all tenth-grade girls, and determined the mean number of sit-ups they could do. Can she make an inference about the population mean for all tenth-grade girls based on the sample?

What is the z-score with a confidence level of 95% when finding the margin of error for the mean of a normally distributed population from a sample?

Which of the following z-values, standard deviations, and sample sizes produce a margin of error of 0.95?

The times it took for 35 loggerhead sea turtle eggs to hatch in a simple random sample are normally distributed, with a mean of 50 days and a standard deviation of 2 days. Assuming a 95% confidence level (95% confidence level = z-score of 1.96), what is the margin of error for the population mean?Remember, the margin of error, ME, can be determined using the formula .

Suppose the mean of a normally distributed population is 300, and 200 simple random samples are drawn from the population. At a 68% confidence level, (one standard deviation from the mean), about how many of the samples’ confidence intervals would you expect to contain the population mean?