Tutorial 6

Tutorial 6 - THE UNIVERSITY OF HONG KONG DEPARTMENT OF...

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3. The net weight of packages of beef sold in a supermarket are labeled "3 pounds." A complaint has been made 2. A company wants to estimate the 99% confdence interval For the liFetime oF inkjet printer heads produced. The 1. 225 ±ight records are randomly selected, giving a sample mean oF 11.6 unoccupied seats. Given that the population Example Class 6 1 THE UNIVERSITY OF HONG KONG DEPARTMENT OF STATISTICS AND ACTUARIAL SCIENCE STAT0302 Business Statistics (Semester 2, 2012/2013) Questions Confdence Interval Given X N ( μ,σ 2 ) , where the population mean μ is unknown and the population variance σ 2 is known. The (1 α )% confdence interval estimate For μ is given by ° ¯ x z α 2 σ n , ¯ x + z α 2 σ n ± where ¯ x is the sample mean oF a sample with size n drawn From the population and P ( Z>z α 2 )= α 2 Determining the sample size The margin oF error is given by halF the length oF a confdence interval. Suppose we require the margin oF error not to be more than a number E at the (1 α )% confdence interval, we need a sample oF size n such that n ² z α 2 σ E ³ 2 standard deviation oF unoccupied seats in a ±ight is σ =4 .1s ea t s ,e
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Tutorial 6 - THE UNIVERSITY OF HONG KONG DEPARTMENT OF...

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