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Unformatted text preview: STATISTICS 321 Spring 2009 Name: Quiz 4 (20 points) This quiz has 2 sides. General formula : (statistic) (margin of error) Parameter Conditions * Statistic Margin of error known x z / 2 . n unknown x t / 2 . s n p n p 10 and n (1- p ) 10 p z / 2 . q ( p )(1- p ) n * Of course, for each of the above case it is important that the sample was selected at random. 1. A researcher at the Medical College of Virginia conducted a study of 60 randomly selected male soccer players and concluded that frequently heading the ball in soccer lowers players IQs ( USA Today , August 14, 1995). The soccer players were divided into two groups, based on whether they averaged 10 or more headers per game, and the IQs were recorded. The summarized data on the IQs for the two groups are presented in the table: Sample size Mean Standard deviation Fewer than 10 headers 35 112 10 10 or more headers 25 103 8 (a) Find a 95% confidence interval for the mean IQ of soccer players who make fewer than 10 headers...
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- Winter '08