# A 90% confidence interval for the proportion

A sample of 150 new cell phones produced by Yeskia found that 12 had cosmetic flaws. A 90% confidence interval for the proportion of all new Yeskia phones with cosmetic flaws is 0.044 to 0.116. Which statement below provides the correct interpretation of this confidence interval? a. There is a 90% chance that the proportion of new phones that have cosmetic flaws is between 0.044 and 0.116. b. There is at least a 4.4% chance that a new phone will have a cosmetic flaw. c. A sample of 150 phones will have no more than 11.6% with cosmetic flaws. d. If you selected a very large number of samples and constructed a confidence interval for each, 90% of these intervals would include the proportion of all new phones with cosmetic flaws. e. none of the above

The standard deviation of a normal population is 10. You take a sample of 25 items from this population and compute a 95% confidence interval. In order to compute the confidence interval, you will use a. the t table because the degrees of freedom will be 24. b. the t table because you have estimated the standard deviation from the sample. c. the z table because the population standard deviation is known. d. the z table because the sample size is small. e. none of the above

You are conducting a one-sided test of the null hypothesis that the population mean is 532 versus the alternative that the population mean is less than 532. If the sample mean is 529 and the p-value is 0.01, which of the following statements is true? a. There is a 0.01 probability that the population mean is smaller than 529. b. The probability of observing a sample mean smaller than 529 when the population mean is 532 is 0.01. c. There is a 0.01 probability that the population mean is smaller than 532. d. If the significance level is 0.05, you will accept the null hypothesis. e. none of the above