| Hand in Friday Monday for sure: DIST. OF XBAR(S) These problems use only the mean and standard deviation. p. 280, 11.7 (Teen cholesterol ) p. 280, 11.8 (lab measurements) For (b) they mean "what should n be?' These problems use the "sample mean of n independent observations from a normal distribution has a normal distribution." theorem (p. 278) p. 280, 11.9 NAEP math scores (n = 1, n = 4) p. 290, 11.37 and 11.39 Pollutants in auto exhausts For 11.39: You might want to know L so that if you tested your 25 cars and found a high value of x-bar, you would be able to compare it with L; if it was greater than L, you would go back to the manufacturer and say "I believe you sold me a batch of bad cars, because the chances of getting an average emission level this high if the exhaust system is working properly is only 1 in 100. It is more reasonable to believe the exhaust system is not working, than that we "are" that 1 in 100 possibility." p. 289-90 11.36 and 11.38 Glucose testing If we use this cutoff level L to say that people (with a mean of 4 tests) over L "have diabetes", then the chances of declaring that someone "has diabetes" when they really are OK (with mean 125mg/dl) is .05. .05 or 5% is the chance of a "false positive" using this protocol, when the real mean is 125. These problems use the Central Limit theorem (p. 281) p. 185, 11.10 What does the CLTh say? p. 286 , 11. 12 SAT scores, n = 1 and 70 p. 286, 11.13, insurance (Hint: find P(Xbar> $275)) p. 298, 11.41 auto accidents p. 298, 11.42 airplane overloads (Hint: to do the problem you have to assume all the seats are taken. Maybe not a reasonable assumption, but if there are empty seats, there's likely not a problem with overweight.) A. (preliminary for Ch. 14) Get 4 slips from the Birkenstock box (Will be outside my door Friday.). Record them, return them. HW: Find their mean xbar. Now xbar is your "point estimate" of the unknown mean of the numbers in the box. Calculate xbar - .841, xbar +.841. This is your "point estimate" plus or minus a "margin of error" of .841. (xbar - .841, xbar +.841) is your "interval estimate" for the unknown mean of the box. |
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