# this is a diffrent one

• Jan 3rd 2007, 09:13 AM
canyouhelpme
this is a diffrent one
Sorry but i am not good at math, can someone help me ,what is the probality of a person contacting hiv in a city with a population of 190,000.with 6,000 people carrying the virus in the city.
• Jan 3rd 2007, 09:16 AM
CaptainBlack
Quote:

Originally Posted by canyouhelpme
Sorry but i am not good at math, can someone help me ,what is the probality of a person contacting hiv in a city with a population of 190,000.with 6,000 people carrying the virus in the city.

Not enough information. Over what period? how many times will they
have unprotected sex? What is the transmission probability per encounter?
Does this depend on sexual practice? Gaye straight? ...

RonL
• Jan 3rd 2007, 09:21 AM
canyouhelpme
sorry
thanks for you reply,im talking a one time encounter with a female using a Condom,what the transmission probality in this one encounter,and lets just say she has been with 20 men 18 protected 2 unprotected
• Jan 3rd 2007, 09:34 AM
CaptainBlack
Quote:

Originally Posted by canyouhelpme
thanks for you reply,im talking a one time encounter with a female using a Condom,what the transmission probality in this one encounter,and lets just say she has been with 20 men 18 protected 2 unprotected

You are supposed to tell us the rate, this is not an epidemiology site
we help with the maths not gathering data.

(don't worry: one encounter, hetro, protected in this case probably <1/100
chance of transmission other things being equal)

RonL
• Jan 3rd 2007, 09:34 AM
ThePerfectHacker
Quote:

Originally Posted by canyouhelpme
thanks for you reply,im talking a one time encounter with a female using a Condom,what the transmission probality in this one encounter,and lets just say she has been with 20 men 18 protected 2 unprotected

Your professor gave you such a question?:confused:

The probability that a person have HIV is:
$\displaystyle p=\frac{6000}{190000}\approx .0315$
(Problem is, we do not know the male/female population. I will assume it is equal then what I said is true).

I will assume when it is protected the probability is zero. Thus, the harlot did it twice with two different men. The 18 make no difference it was protected.
The probability she did contract HIV is (assume unprotected leads to HIV):
$\displaystyle 2(.0315)+(.0315)^2\approx .064$

Thus the probability the harlot is safe is about 94%.
• Jan 3rd 2007, 09:43 AM
CaptainBlack
Quote:

Originally Posted by ThePerfectHacker
Your professor gave you such a question?:confused:

The probability that a person have HIV is:
$\displaystyle p=\frac{6000}{190000}\approx .0315$
(Problem is, we do not know the male/female population. I will assume it is equal then what I said is true).

I will assume when it is protected the probability is zero. Thus, the harlot did it twice with two different men. The 18 make no difference it was protected.
The probability she did contract HIV is (assume unprotected leads to HIV):
$\displaystyle 2(.0315)+(.0315)^2\approx .064$

Even here we have a problem, as we don't know the infection prob. per
encounter, but it is definitly less than 1:)

Quote:

Thus the probability the harlot is safe is about 94%.
There are lots of other things we don't know which make this an impossible
sum, we need to know the hetro infected population, and ...

Also it does not look like homework to me...

All we can say is the use of a condom should make the transmission via
the obvious route unlikley, but there are other transmission mechanisms
about which very little is known.

RonL

RonL
• Jan 3rd 2007, 09:47 AM
topsquark
And, unfortunately, a condom is not a perfect guard against the disease either, as they can break, slip off due to improper use, etc. This factor also should be included.

-Dan
• Jan 3rd 2007, 10:21 AM
canyouhelpme
thanks
thank you for your help everyone