-----Which of the following statements is untrue?

1)The Central Limit Theorem says that, for samples of size at least 30, the average of observations from any single distribution becomes normally distributed.

2) Confidence intervals for population proportions, constructed using z-scores as critical values, are only valid under the Central Limit Theorem.

3) Confidence intervals for population means of normal populations, constructed using z-scores as critical values, are valid even without the Central Limit Theorem

4) The Central Limit Theorem says that, for samples of size at least 30, individual observations from any distribution become normally distributed.

Mr F asks: Which ones do **you** think are untrue and why?
-----Which of the following is a true statement?

1) The width of a confidence interval for a population proportion will change from sample to sample, for a fixed confidence level.

2) The width of a confidence interval will always change from sample to sample, regardless of what we're estimating (mean or population).

3) The width of a confidence interval for a population mean will change from sample to sample, for a fixed confidence level.

4) The width of a confidence interval will never change from sample to sample, regardless of what we're estimating (mean or proportion).

5) A 90% confidence interval will be the same for every sample taken.

Mr F asks: Which ones do **you** think are true and why?