# Math Studies by fjzhangxiaoquan

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```									Prob & Stat            Chapter 11 and 13     Review

USA Today reported that the state with the longest mean life span is Hawaii, where the
population mean life span is 77 years. A random sample of 20 obituary notices in the
Honolulu residents:

72     68      81      93      56     19     78      94      83     84
77     69      85      97      75     71     86      47      66     88

Assuming the life span in Honolulu is approximately normally distributed, does this
information indicate that the population mean life span for Honolulu residents is less than
77 years? Use a 5% level of significance.

A trainer claims by taking a special vitamin, a weight lifter can increase his strength.
Eight athletes are selected and given a test of strength, using the standard bench press.
After two weeks of regular training, supplemented with the vitamin, they are tested again.
Is there significant evidence at the 5% level that the vitamin increases strength? Assume
the weights are normally distributed.

Athlete        1            2   3   4        5       6       7   8
Before Vitamin 210          230 182 205      262     253     219 216
After Vitamin  219          236 179 204      270     250     222 216

The table below shows the responses of a randomly chosen sample of senior citizens to a
survey dealing with weight and whether they have diabetes.

Light            Medium               Heavy           Obese
Diabetic            11               19                   21              38
Non-Diabetic        79               68                   74              53

Test at a 1% level whether there is a link between weight and diabetes.

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