Statistics Test: Confidence Intervals and Sampling, Exams of Probability and Statistics

Download Statistics Test: Confidence Intervals and Sampling and more Exams Probability and Statistics in PDF only on Docsity! MAT 121 Test4C December 3, 2008 Instructions: Write the answers and show all your work on the test paper. (You may submit additional sheets of paper if you need more room, but make sure your name is on each additional sheet.) If you use a calculator, write out all steps and their results as if you were working the problem by hand. You may use your text. Problem 1. (14 points) A total of 26 of the apples in a random sample of 200 apples from the Smith family orchard had one or more worms in them. Construct a 95% confidence interval for the proportion, p, of all Smith family apples that contain worms. Problem 2. (8 points) Professor Lockhart gave each member of his class a different random sample of 50 M&M candies and asked each one to construct a 90% confidence interval for the population proportion, p, of blue M&Ms based on the sample they were given. Amazingly, all 75 students constructed a correct confidence interval. a. Explain in one sentence why the intervals were not all of equal width. b. About how many of the intervals would we expect to contain the true value of p?