Geek Puzzle

Irene · Post by **Irene** » Fri Oct 19, 2007 11:08 am

DoubleDutch wrote:1+1=0 ....

1 + 1 logically is 0 because p + p = 0

+ is a logical sign for XOR

http://en.wikipedia.org/wiki/XOR

Didn't think about that.. cool! ^o^

DoubleDutch · Post by **DoubleDutch** » Fri Oct 19, 2007 11:11 am

I've edited my post its now cooler!

Irene · Post by **Irene** » Fri Oct 19, 2007 11:21 am

DoubleDutch wrote:I've edited my post its now cooler! ;)

Haha ^o^

Derek · Post by **Derek** » Fri Oct 19, 2007 4:29 pm

@citystate, you're correct!

Rook Zimbabwe · Post by **Rook Zimbabwe** » Fri Oct 19, 2007 8:53 pm

This just explains why I don't let my computer do my income tax! No matter how it is added up I still get 0.00 back!

If we encounter our college girlfriend with a baby, she says she has 2 children. This one is a boy named Rook Jr. Knowing she has exactly two children, given that at least one of them is a boy, what is the probability that both of her children are boys?
or

If three hens lay three eggs in three days, how many eggs does a hen lay in one day?

Derek · Post by **Derek** » Fri Oct 19, 2007 8:58 pm

75% chance both are boys.

1 third of an egg.

Nik · Post by **Nik** » Fri Oct 19, 2007 8:59 pm

1 hen lays 1 egg in three days, that's a probability of 33.33% that she lays an egg at any given day in a time space of three days, because she can't lay a 1/3 egg per day

The probability of both children being boys is 50% because the chance that a child is a boy is roughly 50% no matter how many childen you already have. And if she gets a girl it's not two boys but if she gets a boy it's two boys.

Derek · Post by **Derek** » Fri Oct 19, 2007 9:03 pm

I figured that she was already half way there (50%) and the chance of the other being a boy was 50/50 (of the remaining 50%=25%) therefore 75%.

Would be intersting to see the hen that lays thirds of an egg.

Rook Zimbabwe · Post by **Rook Zimbabwe** » Fri Oct 19, 2007 9:18 pm

1/3 of an egg is right...

75% nope...

the option are: 2 girls (we can throw out), boy and girl(we can ignore because it isn't 2 boys), and 2 boys (1 of 3 and the only one we were asking for 1 of 3 is 1/3)

33%

Nik · Post by **Nik** » Fri Oct 19, 2007 9:35 pm

But you said "given that at least one of them is a boy" so there is no girl,girl option, or did I get something wrong here

Rook Zimbabwe · Post by **Rook Zimbabwe** » Sat Oct 20, 2007 2:20 am

Simple... girl/girl is ONE of the possibilities... but we can discard it as we know at least ONE of the children is a boy... The possibility still exists that she could have had two girls.

The knowledge that one child is a boy allows us only to assume the following 2 out of 3 scenarios:

girl/boy and boy/boy

The total possibility of all combos for 2 children (assuming normal birth with no Hermaphrodites and no Freemartins) is thus:

1- Girl/Girl
2- Boy/Girl
3- Boy/Boy

Knowing she has exactly two children, given that at least one of them is a boy,

One of the KEY words is "Given" which means we must include ALL possibilities in our answer.

We are asking the percentage of probability that she has Boy/Boy. There are 3 combinations possible. We can delete the Girl/Girl possibility. This deducts 33% (or 1/3 possibilities) she could have Boy/Girl but we don't care about that which deducts the second of the 3 possibilities leaving only the last selection as a probability of what we wanted out of the three possible selections or 1/3 (33%.)

Statistics are slippery... Wait till you get to Graduate School and have to take a class before you are allowed to write your Dissertation!!! The section on my dissertation on my statistical methodology was about 96 pages long.

Nik · Post by **Nik** » Sat Oct 20, 2007 2:21 pm

So it probably was a language barrier thing.

Rook Zimbabwe · Post by **Rook Zimbabwe** » Sat Oct 20, 2007 9:28 pm

That could entirely be the case...

Sorry!

I can see where you would think 50% because you dismissed the Girl/Girl possibility

That leaving Boy/Girl and Boy/Boy there only 1 of 2 (1/2) would be Boy/Boy and therefore 50%.

Then again it could simply be a Elvis Clone left by the space aliens to promote their future enslavement of the Human race...

Rook Zimbabwe · Post by **Rook Zimbabwe** » Mon Oct 22, 2007 3:17 pm

Boy can I kill a thread or what?

blueznl · Post by **blueznl** » Mon Oct 22, 2007 10:44 pm

50% of all statistics are false. The rest is made up.
By the way, lessee how smart we are. What was first, the chicken or the egg? (There is actually an answer to that one...)