Biostatistics
Fernando et al. (2003) studied drug-sharing among injection drugs users in the South Bronx in New York City. Splitting a bag – a practice where heroin is shared between two people after dissolving it in a common cooker prior to injection– is a known high risk factor for HIV exposure.  Interviews with drug users in a residential treatment facility provided the following information.
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 Gender
Have you split drugs
Total
Yes (Y)
No (N)
Male (M)
390
321
711
Female (F)
179
131
310
Total
569
452
1021
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What is the probability that a person chosen at random will have split drugs
What is the probability that a person chosen at random is not female
What is the probablity that a person has split drugs given they are a male
WHat is the probablility that someone chosen at random will be a female or will not have split drugs
Given taht someone has split drugs, what is the probablity that they are femaleÂ