BIOS 603

• Learning Objective 5

  Problems 3.36-3.42 pages 68, 3.55 and 3.56 page 69
  Answer
  
  1. You flip a coin three times. The coin is fair so that the probability of a head is .5. What is the probability that
  

      a.  all three flips are heads?
      b.  the first is a head or the second is a head?
      c.  you get two heads?
      d.  you get two heads given that the first is a head?
      e.  the second is a head given the first is a head?
  

  Answer
  
  2. Work the problem again using an unfair coin. The probability of a head is .6.
  
  On line help
  
  Answer
  
  

• Learning Objective 6

  Problems 3.12 page 67, 3.57 and 3.58 page 69, 3.66 page 70
  Answer
  
  3. The following data was reported by the CDC in The Morbidity and Mortality Weekly Report, 1990, 39(14), 228-232. The Florida Department of Health and Rehabilitative Services interviewed fifty three patients with hepatitis A and sixty four of their disease free eating companions concerning their oyster consumption.

                             Oysters
                            No    Yes  Total
                Cases        2     51    53   
                Controls    31     33    64
                Total       33     84   117
  
  What is the probability that:
  
  a.  A person in this sample was a case?
  b.  A person ate oysters given that s/he was a case?
  c.  A person ate oysters given that s/he was not a case?
  d.  A person ate oysters and was a case?
  
  Are case status and oyster consumption independent?
  

  
  On line help
  
  Answer
  
  

• Learning Objective 7

  Problems 3.49 page 69, 3.59 page 69
  On line heop
  
  Answer

• Learning Objective 8

  Problems 3.60 page 70
  On line help
  
  Answer

• Learning Objective 9

  Problems 3.85-3.88 page 72
  
  The prevalence of chlamydia is 1%. The sensitivity of a screening test is 92% and the specificity equals 99%. A woman is told that she has a positive test result. What is the probability that she has chlamydia?
  On Line Help Answer

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