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Question

66% of students at one college drink alcohol regularly and 13% of those who drink alcohol regularly suffer from depression. What is the probability that a random selected student drinks alcohol regularly and suffers from depression

Answer 1

let P (D) be the probability that a student is depressed and P (A) the probability that a student drinks alcohol regularly

 

then the conditional probability would be given by :

 

 

P ( D ! A) = P ( D & A ) / P ( A)

 

P ( D & A ) = P (A) * P ( D ! A)

 

                 =  0.13 * 0.66

 

                 =   0.0858 = 0.09

 

that is the probability that a selected student would drink alcohol regularly and suffer from depression