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Title: Stats Question... Post by: benchiefjr on December 06, 2006, 11:57:13 PM A small-engine repair shop has found that repair times have a standard deviation of 28 minutes. A new repair system is being tested, and a sample of 16 repair times produces a standard deviation of 17.3 minutes. At the 0.01 level of significance, test the claim that the new system produces a lower standard deviation than the old system.
H0 : o >= 28 H1 : o < 28 A study of smoking habits is conducted in a certain country. In a sample of 150 rural and suburban residents, 44% smoke. In a sample of 400 city residents, 52% smoke. At the 0.03 level of significance, test the claim that city residents comprise a larger proportion of smokers than rural and suburban residents. If anyone could do just ONE of these, that'd be much appreciated. I still don't get this... any idea on these two? |