Riddles

[aphexcoil]

Quote from Mr Subliminal:

Aphie, you should remember this! The old Bayes' Theorem :

P(A|B) = (P(B|A)*P(A))/P(B)

Let A = the event of having the disease
Let B = the event of testing positive

P(A|B) = (1*(1/500))/((1/500)+(499/500)*(0.05))

= 20/519

That class was actually one I was trying very hard to forget.

 

[Mr Subliminal]

Quote from darkhorse:

mr sub came up with 20/519 which is even closer @ 3.85%

though i must say mr. sub you used a lot of high falutin' figgerin

Even closer? You seem to imply that your solution is the correct one. It is elegant, but still an approximation. Why not go the whole way?

if the screen test has a 5% false positive rate and 1 person out of 500 is actually infected, that means you will see 1 real case and 25 false positives in each hypothetical group of 500 tested

Not quite. That means you will see 1 real case and 499*0.05, or 24.95, false positives in each hypothetical group of 500 tested.

Therefore you can calculate the probability simply dividing 1 by 26 = 3.846

Or better still, dividing 1 by 25.95 = 3.853% = 20/519.

Using high falutin' figgerin, like Bayes' Theorem, has always kept me out of trouble

 

[stu]

Quote from Mr Subliminal:

Aphie, you should remember this! The old Bayes' Theorem :

P(A|B) = (P(B|A)*P(A))/P(B)

Let A = the event of having the disease
Let B = the event of testing positive

P(A|B) = (1*(1/500))/((1/500)+(499/500)*(0.05))

= 20/519

Notes
(1) P(A|B) is the probability that A occurs, given that B has occurred, known as conditional probability.
(2) Given no other information, I'm assuming there are no false negatives.

http://www.elitetrader.com/vb/showthread.php?s=&postid=177532#post177532

Good riddle dark, and Very well explained Mr Sub !
Bayes's Theorem for conditional probabilities, excellent, well done!!

I knew that


But I found it easier to calculate by using the now famous equation theorem (‡ f+g / fp) which incorporates 3 grounded fireboats, a glass of water and 2 frozen penguins whislin' Dixie

Does anyone know how to remove pesky Amoebas outa my keyboard ?

Thanks

 

[aphexcoil]

In a fair lotto, there is an equal chance for any combination of numbers to come up.

However, some number combinations are much better than others to pick when attempting to win. How is this possible?

 

[Mr Subliminal]

The theory goes that one should pick numbers over 31; not because they have a better chance of being drawn, but because if they do get selected, your chance of sharing the prize with others goes down. Why 31? I'll leave that for others to explain.

 

[aphexcoil]

Quote from Mr Subliminal:

The theory goes that one should pick numbers over 31; not because they have a better chance of being drawn, but because if they do get selected, your chance of sharing the prize with others goes down. Why 31? I'll leave that for others to explain.

You're just too smart.

a) Don't pick patterns on the selection card.
b) Don't pick patterns like "1-2-3-4-5-6"
c) Be as random as possible

But yep, you got it!

 

[Mr Subliminal]

I can understand a thread not having any replies, but no views? I just took a snapshot, so go ahead and deflower.

 

[Mr Subliminal]

A little quiz to test your knowledge of ET. All the answers can be found fairly easily, so please, no cheating.

(1) How many forums currently in ET?

(a) 12
(b) 16
(c) 20
(d) 24

(2) Shreddy is

(a) Don Bright's secretary
(b) nitro's dog
(c) Longshot's cat
(d) mytwocents' teddy bear

(3) murray t turtle's favorite King is

(a) Larry
(b) Kong
(c) Solomon
(d) Don

(4) Babak has a connection to

(a) Athens
(b) Haifa
(c) Istanbul
(d) Beirut

(5) Ditch lives in

(a) Holland
(b) Belgium
(c) France
(d) Portugal

(6) A random letter generator was used to create this handle

(a) pitufo
(b) iiphos
(c) jaqaw
(d) redzuk

 

[Babak]

I'll take a stab at it:

1]c
2]b
3]b
4]-
5]a

 

[Prince Philip]

Quote from Maharaja:

My all time favorite...

Suppose you're on a game show, and you're given the choice of three doors. Behind one door is a car, behind the others, goats. You pick a door, say number 1, and the host, who knows what's behind the doors, opens another door, say number 3, which has a goat. He says to you, "Do you want to pick door number 2?" Is it to your advantage to switch your choice of doors?

clearly. because the reverse odds have changed. No challenge to the gordian there.