Question

Probability Help!!!

The probability that a randomly chosen male has a drinking problem is 0.10 . Males who have drinking problems are three times as likely to have marriage problems as those who do not have a drinking problem. What is the conditional probability that a male has a drinking problem, given that he has marriage problems?

Answer 1

spose we put all the people with marriage problems into one room ... how many people would be in the room?

Answer 2

ummm only marriage? well how would know?

Answer 3

the actual number of people in the room is not important .. it can be any number we chose.

but given, that we have a room full of marriage issues ... what is the ratio of drunks to sobers?

Answer 4

3 drunks to 1 sober right?

Answer 5

1/3

Answer 6

So I figured it was P(M and D) = 3 P(M and D')

Answer 7

and P(D) = 0.10 and we want to find P(D | M)

Answer 8

well, 3 to 1 sounds better to me ... drunks to sober

so lets say there are 4 people in the room. 3 of them are drunks.

whats that give us as a probability?

Answer 9

you asking whats the probability that out of those 4 they have marriage issues or just out of the 3

Answer 10

P(D) is not relevant to the question. i believe it is just added info to see if you know what you are looking for.

Answer 11

spose we have 4 people in the room ... given this set of people, what is the probability that we can pick a drunk?

in other words: what is the probability of picking a drink; given a room full of people with marriage issues.

Answer 12

3/4 would be right

Answer 13

yes

Answer 14

given that the answer choices are .05, .10, .15, .20, .25.... That couldn't be right... i see what you are saying as far as this logic goes... but it feels like something is being left out.

Answer 15

hmm, lets see if im reading it correctly, or at least as correct as what makes sense :)

The probability that a randomly chosen male has a drinking problem is 0.10 .


Males who have drinking problems are three times as likely to have marriage problems as those who do not have a drinking problem.
**** this is a 3 drunks to 1 sober ratio right?

****So of the subset of 'has marriage problems', we would expect that 3 out of 4 people in the room are drunks.


What is the conditional probability that a male has a drinking problem, given that he has marriage problems?
\[P(D|M)=\frac{P(D\cap M)}{P(M)}\]
or written another way
\[P(D|M)=\frac{n(D\cap M)}{n(M)}\]

Answer 16

we arent given the number (or probability) of marriage issues. It is just hinted that the ratio is 3 to 1, or 3n to n

right? i cant see the error in my thoughts.

Answer 17

Well to me, and what I can't decide which I have a big feeling is part of the problem, well cause every problem in this text i have ever come across uses absolutely every piece of information... is the 3 to 1 part... now I can't figure out if that means
P(M and D) = 3 P(M and D') or P(M | D) = 3 P(M | D')

Answer 18

And you use that info along with the P(D) = .10 and P(D') = .9 to solve for P(D | M)

Answer 19

maybe DnM = .75?