In a public opinion survey, 80 out of a sample of 100 high-income voters and 55 out of a sample of 80 low-income voters supported the introduction of a new national security tax. a/ Estimate, with 95% confidence level, the true proportion of low-income people who will vote for the introduction of the tax.
b/ Can we conclude at the 5% level of significance that the proportion of high-income voters favoring the new security tax is 10% higher than that of low-income voters?

If your score on your next statistics test is converted to a z score, which of these z scores would you prefer: minus2.00, minus1.00, 0, 1.00, 2.00? why? a. the z score of 2.00 is most preferable because it is 2.00 standard deviations above the mean and would correspond to the highest of the five different possible test scores. b. the z score of 0 is most preferable because it corresponds to a test score equal to the mean. c. the z score of minus2.00 is most preferable because it is 2.00 standard deviations below the mean and would correspond to the highest of the five different possible test scores. d. the z score of minus1.00 is most preferable because it is 1.00 standard deviation below the mean and would correspond to an above average