(July 11, 2015 at 2:07 am)robvalue Wrote:(July 9, 2015 at 7:06 pm)pocaracas Wrote: In 10 spouses, odds are higher that one of them will cheat you than with just one spouse.
If 10% of all people cheat, then, if you have 10 spouses, one of them is 100% likely to cheat, statistically speaking.
But if you only have 1 spouse, you have a 10% chance of having a cheating spouse.
The point being made here is valid, but I'd like to address the mathematics
In the above scenario, if we say that someone has a 10% chance of cheating at some point in their life:
The probability that at least one of them cheats at some point = 1 - The probability than none of them ever cheat
[They are exclusive and exhaustive events and so cover all possibilities with no overlap]
This probability, assuming all the people act independently is then:
1 - (90%)^10 = 1 - 0.3486784401... = 0.65 [To two decimal places. We need 10 non-cheaters in a row so we multiple their probability]
So the probability that at least one of the group cheats at some point in their life is slightly under two thirds.
What could instead be said is that the average number of people from the 10 who will cheat at some point in their life will be 1. This is probably what was meant in the first place to be fair
My point wasn't which situation is more likely to have a cheater. My point was if 1 out of 10 cheats your chance of an std is no different than 1 out 1 cheating, I was already assuming a cheater in both cases.
