Tugas Iv.docx

Tugas IV: 1) The U.S. Food and Drug Administration (FDA) recently approved the marketing of a new chemical solution, Caridex, which dissolves cavities. In a study conducted by dental researchers at Northwestern University, 21 of 35 patients with cavities preferred treatment with Caridex to drilling. Estimate the true proportion of dental patients who prefer having their cavities dissolved with Caridex rather than drilled. Use a 99% confidence interval and interpret the result. 2) A chemist has prepared a product designed to kill 60% of a particular type of insect. What sample size should be used if he desires to be 95% confident that he is within 0.02 of the true fraction of insects killed? 3) Bottling company has a problem with the new filling mechanism for 2-liter bottles. Using a sample of the filled volume of 20 bottles they have the following results: 1.95 1.96 1.98 1.99 2.00 2.00 2.01 2.01 2.01 2.01 2.02 2.02 2.03 2.03 2.04 2.04 2.05 2.06 2.08 2.10 Find the 95%-confidence interval for population standard deviation. Assume the filled volume is distributed normally. 4) A precision instrument is guaranteed to read accurately to within 2 units. A sample of 4 instrument readings on the same object yielded the measurements 353, 351, 351, and 355. Find a 90% confidence interval forn the population variance. What assumptions are necessary? Does the guarantee seem reasonable?