Stat 538: Biostatistics I 
 HW 5 due TUESDAY October 11th in LECTURE.

 In each problem make sure you clearly define the population proportion
 or mean (which ever is relevant) in the context of the problem.

 Also, make sure to write a brief, coherent summary for each problem.


 1. Do this problem in Minitab

    A 1997 survey conducted by M.I.T. reported that 25% of the 1,016 adults
    surveyed would be willing to support tax hikes to fund AIDS research.
    Find a 95% CI for the proportion p of all adults that favor such a
    tax hike.

    Suppose it was known that in 1990 that the proportion of all adults
    willing to support tax hikes to fund AIDS research was .20. Is
    there evidence that the proportion of adults in 1997 willing to
    spring for tax hikes for this purpose has changed since 1990?
    Carry out a test to answer this question. Use alpha=.05.

    Is the result of the CI consistent with the test? Explain.

 2. Do this problem in Minitab

    The annual incidence of asthma in the general U.S. population among 
    male children 0-4 years old is known to be 1.4%. Suppose that we wish 
    to assess whether the population proportion of asthmatic male children
    aged 0-4 years old in households with smoking mothers differs from the
    overall U.S. proportion of .014. A sample of 500 boys from the population
    is selected, and 10 are found to be asthmatic. Carry out the appropriate 
    test of interest at the .05 level, and write a conclusion

 3. Do this problem in Minitab.

    The following data are the total cholesterol levels (TCL) for a sample
    of 14 young adult males (aged 25 years or less) on the Kaiser Health
    plan in California:

       225  237  219  211  216  244  216  222  208  202  195  227  218  195

    Suppose it is believed that the mean TCL of all adult males in the
    United States is 210. Is it plausible the mean TCL of all young adult
    males on the Kaiser plan is the same as the U.S. male mean TCL? Test
    at the 5% level. Be sure to state any assumptions needed to carry out
    the test and check whether these assumptions are reasonable. Also,
    construct and interpret a 95% CI for the Kaiser population mean.


 4.  Do this problem in Minitab.

     Many scientists have expressed concern about the use of nitrates
     as meat preservatives. In one study, bacteria cultures were grown
     in a medium containing nitrates. The rate of uptake of radio-labeled
     amino acid was then determined for each one, yielding the following
     observations:

      7251  6871  9632  6866  9094  5849  8957  7978  7468
      7064  7494  7883  8178  7523  8724

     Suppose it is known that the true mean uptake for cultures without
     nitrates is 8000. Does the data suggest that the addition of nitrates
     results in a decrease in true mean uptake? Test the appropriate
     hypotheses at the 10% level.  Be sure to state any assumptions needed
     to carry out the test and check whether these assumptions are
     reasonable.