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 female?Â