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4. Upper confidence limit = 0.820 Lower confidence limit = 0.490 5. Upper confidence limit = 0.715 Lower confidence limit = 0.350 B. Find the length of the confidence interval given the following data: 6. s = 5.36, n = 350, confidence level: 99% 7. s = 2.35, n = 250, confidence level: 99% 8. s = 1.20, n = 200, confidence level: 95% 9. s = 8.15, n = 29, confidence interval: 99% 10. s = 3.25, n = 17, confidence interval: 95%\fI. State the null and the alternative hypotheses of the following statements. (4 points each) 1. A car dealership announces that the mean time for an oil change is less than 15 minutes. 2. A company advertises that the mean life of its furnaces is more than 18 years. 3. A consumer analyst reports that the mean life of a certain type of automobile battery is not 74 months. 4. A transportation network company claims that the mean travel time between two destinations is about 16 minutes. II. Determine if one-tailed test or two-tailed test fits the given alternative hypothesis. (2 points each) 1. The average age of doctors in Las Pinas is 35 years. 2. The proportion of senior male students' height is significantly higher than that of senior female students. III. Illustrate the rejection region given the critical value and identify if the t-values lie in the non-rejection region or rejection region. (2points each) 1. critical t-value of -2.086 computed t-value of -2.096 2. critical t-value of $1.071 computed t-value of 1.01 IV. Identify the appropriate test statistic to be used in each problem. (2 points each) 1. Based on the report of the school nurse, the average height of Grade 11 students has increased. Five years ago, the average height of Grade 11 students was 170cm with standard deviation of 38cm. She took a random sample of 150 students and derived the average height of 165cm. 2. A manufacturer of tires claim that their tire has a mean life of at least 50,000kms. A random sample of 28 of these tires is tested and the sample mean is 33,000kms. Assume that the population standard deviation is 3,000kms and the lives of the tires are approximately normally distributed. 3. In the population, the average IQ is 100. A team of scientists wants to test a new medication to see if it has either a positive or a negative effect on intelligence, or no effect at all. A sample of 30 participants who have taken the medication has a mean of 140 with a standard deviation of 20. Did the medication affect intelligence? Alpha=0.05