STP 226, Spring 2021 Final Exam Study Guide 24. Being an obvious candidate, the rapper Chamillionaire has decided to run for president in 2024. His advisors want to know what chances he has for winning in Arizona's primaries, and they want to be at least 99% confident about the proportion of voters that support him will be within 1% of the true proportion. How many voters should be surveyed to achieve their goal? 25. From a sample of 45 students exam scores, it was found that there was a mean score was 75 and a standard deviation of 5. Assume the distribution of exam scores is normal. a. Construct and interpret a 95% confidence interval for the true mean score. b. Construct and interpret a 99% confidence interval for the true mean score. c. Which interval is less accurate for estimating the true mean score? Does this make sense? 26. Two programmers, Al and Hal, are claiming to have written code to perform a particular result faster than the other. Both programmers made 20 attempts with their code using a computer from a third party. Al's code performed the calculation with an average of 135.7 seconds and a standard deviation of 4.8 seconds, while Hal's code performed the calculation with an average of 134.2 seconds with a standard deviation of 5.7 seconds. With a significance level of 0.05, test the claim that the true mean computation time of each programmer's code is the same as the other's. a. State the hypotheses Ho and H1- . Evaluate the appropriate test statistic. C. Find the critical value and rejection region for this test. d. Decide whether to reject Ho or not. e. Interpret the decision. 27. The high and low temperatures, measured in degrees Fahrenheit, of each day in a given summer week were recorded in the table below High Temperature Low Temperature 107 85 101 82 96 79 104 74 103 76 a. Calculate the linear correlation coefficient between the high and low temperatures. b. Briefly interpret what this value tells you about the data