Okay, let's talk semantics and not math.
The odds of you picking the chip with the green side are 1/2. Your choice of the word "I show" implies that you decided which side to reveal.
I'd have to say if you "showed" the green side, the odds were 100% you picked the one with the green side. But what would be the fun in that
It has little to do with semantics. I don't need to have decided which side to show.
What matters is that it was red. Whether random or picked makes no difference (in this sample). I'm pulling it random, we look at it at the same time and we simply see its red. That however is information you cannot simply ignore. Before we looked chances that it was red were 3/4 but after we looked, and saw it was red, the chance for it is 1.
This is the very mistake that inspires KK's thinking and strategy. Statistics are a very peculiar field in mathematics - one can be a genius at calculus, algebra, geometry .. and be a noob at statistics. Compared to other fields of maths it is very very very contra-intuitive. You cannot trust your common sense there you have to trust the numbers and the formula's.
KK, did someone mention the bomb example here yet ? The chance to have a bomb on an airplane is one in a million, the chance to have two bombs is 1 in (million * million). So I always take a bomb on the plane. I'd have to get super-unlucky then instead of normal unlucky
. Of course if you take the bomb in the plane, the chance of that is 1, and the chance of a second bomb is 1 in a million again. If you search a random plane, and you find a bomb, the chance of a second bomb is also just one in a million. Before you start searching the chance of finding a second bomb is one in a (million*million).
If the chance of having an unlucky session is 9 in 10, then before you play the chance for two unlucky sessions is 81 in 100 or 8.1 in 10. So if you lose one we call it unlucky, if you lose both we call it very unlucky.
you play one session.
9 times this is unlucky. (9/10)
1 time its lucky (1/10)
we play a new session
9 times its unlucky (9/10)
1 time its lucky (1/10)
the combined outcomes will be p1 * p2
so 9/10 * 9/10 that both are unlucky so we are very unlucky.
and 1/10 * 1/10 that both are lucky
and 1/10 * 9/10 first lucky, second unlucky
and 9/10 * 1/10 first is unlucky, second is lucky.
between the two sessions, if you lost the first one, the chance of becoming very unlucky is 9/10
AND NOT 81/100. You already have unlucky, that is certain. you need another unlucky to become very unlucky .. coming at exactly the same odds as your first unlucky.
so before you play you have 81% chance of becoming very unlucky, but after one session this chance goes either to 0 (if you won the first we cant become very unlucky anymore), or 9/10 .. if we lost the first we now have 90% chance of becoming very unlucky ( and not 81% even tho only 81% of any two consecutive sessions would be very unlucky).
Cheers,
Enzo