Odds

dvae

Something i sometimes wonder about.
I leave my house and travel in to the city center.
On the other side of town some one famous lets say Gay Byrne leaves his home and travels in to the city center. Now we are both walking from opposite ends of the street and come face to face with each other,
Now just as we pass each other by i look at Gay Byrne and say to myself "wow thats Gay Byrne whats the odds of meeting him".
Gay Byrne just walks past minding his own business never even noticing me.
For me the odds of meeting Gay Byrne are lets just say 10,000/1, for him the odds of meeting me dvae are the same.
Before Gay Byrne left his house would you have given him a 10,000/1 chance of meeting a stranger. Id say no.

gondorff

Yeah that's a tricky one.

If you plug yourself and Gay Byrne into the following equation:



You should get a clearer sense of what you are looking for.

Hope that helps.

gerry87

There's only one Gay Byrne. I'd say there's at least 2 of you.

LeixlipRed

I'd say it's impossible, isn't Gay Byrne out chasing drunk drivers all the time these days?

Mellor

dvae wrote: »

Something i sometimes wonder about.
I leave my house and travel in to the city center.
On the other side of town some one famous lets say Gay Byrne leaves his home and travels in to the city center. Now we are both walking from opposite ends of the street and come face to face with each other,
Now just as we pass each other by i look at Gay Byrne and say to myself "wow thats Gay Byrne whats the odds of meeting him".
Gay Byrne just walks past minding his own business never even noticing me.
For me the odds of meeting Gay Byrne are lets just say 10,000/1, for him the odds of meeting me dvae are the same.
Before Gay Byrne left his house would you have given him a 10,000/1 chance of meeting a stranger. Id say no.

He was 10,000/1 to meet you, dvae, not a stranger.

A stranger is a guaranteed if he walks through town. Sure its full of strange people.
It was just lucky that the strange person he met today was you.

And yes, I just called you a strange person.

Unsay Moon

You have said that the odds of you meeting Gay Byrne are 10,000 to 1 in your situation after you have already laid your eyes on him. Is it a 10,000 to 1 chance that you will go over and introduce yourself?

Nevertheless, In this situation:
The odds of you meeting Gay Byrne are 10,000 to 1.
The odds of Gay Byrne meeting you are 10,000 to 1.

YOU are a stranger to Gay Byrne and you have just defined the situation as having a 10,000 to 1 chance of Gay Byrne meeting you. So the answer to your question will be yes. However, there can be a different chance if you are talking about him meeting ANY stranger.

Okay, lets assume that you are really rather chummy with Gay Byrne. In this case you are not a stranger and a stranger is defined as somebody other than you. It is now impossible for to get any one chance from this situation. The reason that the chance of you meeting Gay Byrne is so small may be to do with something other to the number of people in town that day.

If there was nobody in town that day except you and Gay Byrne because everybody else happens to jump out of existence and leave you to repopulate the earth with Gay Byrne then there is a possibility that both you and Gay Byrne are both wearing blindfolds and you will not meet each other.

The only people you have defined actually exist in this situation are you and Gay Byrne. There is a 1 in 10,000 chance you will meet him in this situation. There is also a chance that nobody will meet Gay Byrne. There is a chance that everybody alive will meet Gay Byrne. So the chance is anything.

Summary
If you are a stranger to Gay Byrne then the answer to your question is 'Yes' - there is a 10,000 to 1 chance of him meeting a stranger and possibly a different chance of him meeting any stranger if there are more than 2 people in town. If you know Gay Byrne quite well then the chance of him meeting a stranger is anything because you haven't defined the people in town.

I hope I am of some help.

Rick Deckard

My musings are similar,

I'm driving down Dorset St. Sitting at lights, see a random stranger (one of the ~1.2m people living in Dublin) walking down the street.

I drive on about my business, what are the chances of seeing that man again, while sitting at the same lights, at the same time of day, in the future?

1 in 1.2m every day?

gerry87

peatcass wrote: »

My musings are similar,

I'm driving down Dorset St. Sitting at lights, see a random stranger (one of the ~1.2m people living in Dublin) walking down the street.

I drive on about my business, what are the chances of seeing that man again, while sitting at the same lights, at the same time of day, in the future?

1 in 1.2m every day?

If you pick out the person the first time you see them then yea, 1 in 1.2m per day.

Seeing him at any stage in the next 60 years would be 1 - (1-(1/1200000))^(365*60) = 0.0180844847. So about 1 in 50 chance. (With a heapload of assumptions)

The odds of seeing the same person at the lights twice would be different, say you see 20 people at the lights, then you could see any of those 20 people the next day. If you see a different 20 people the second day then there's 40 to choose from for the 3rd day so seeing a person for the 2nd time on the third day i think would be 1 in 300k and so on.

As with all these things, it depends a lot on exact wording.

fergalr

peatcass wrote: »

My musings are similar,

I'm driving down Dorset St. Sitting at lights, see a random stranger (one of the ~1.2m people living in Dublin) walking down the street.

I drive on about my business, what are the chances of seeing that man again, while sitting at the same lights, at the same time of day, in the future?

1 in 1.2m every day?

Assuming that you aren't being very exacting in your requirements for 'same time of day' and that you drive there every day, probably much higher than 1 in 1.2m

Most people really follow very regular patterns.
Its quite probable that if he walks down there one day, he walks down there every day; if you are passing by regularly, its much more likely you'll see him than another randomly chosen member of the population of Dublin (which was arbitrary in itself - why 'Dublin' and not 'Ireland', or 'Drumcondra')