The fascination of Maths thread

[Bagpuss]

Indeed. The maths are very very interesting. Take 85 people from uk. 5000 primary schools in total. 0.5 chance that 2 of the 85 went to same primary school.

I did some stats in my final year of Maths degree at Exeter. And the above still freaks me!

Presumably 85 people at random?

[mudskipper]

But sometimes you come across maths in 'proper' books.

Mark Haddon's 'Curious Incident of the Dog in the Night-Time' (OK - it's a kids' book, but that's about my level) presents the following problem (based on a real American game-show)

You're on a game show and you have 3 doors: A, B and C. Behind 2 of the doors are goats, behind one door is a car. Let's say you pick door A. The game show host opens door B, and reveals a goat. Should you stay with door A or should you change your answer?

[fckvwls]

But sometimes you come across maths in 'proper' books.

Mark Haddon's 'Curious Incident of the Dog in the Night-Time' (OK - it's a kids' book, but that's about my level) presents the following problem (based on a real American game-show)

You're on a game show and you have 3 doors: A, B and C. Behind 2 of the doors are goats, behind one door is a car. Let's say you pick door A. The game show host opens door B, and reveals a goat. Should you stay with door A or should you change your answer?

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

Always change

[mudskipper]

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

Always change

Yes - but it does make your brain hurt! If there were 100 doors, you picked one and the host opens 97 - much easier to see why you must change then.

[Bagpuss]

Quite a good example of baysian statistics, i.e you have a prior probability which you can update with new information to give you a more accurate estimator.

[BrilloPad]

Presumably 85 people at random?

Absolutely.

[BrowneIssue]

You're on a game show and you have 3 doors: A, B and C. Behind 2 of the doors are goats, behind one door is a car. Let's say you pick door A. The game show host opens door B, and reveals a goat. Should you stay with door A or should you change your answer?

No, no, no, no, no.

The classic incorrect question.

"The game show host opens door B, and reveals a goat..." should be:

"The game show host, who knows where the car is, opens another door to intentionally reveal a goat (and never the car)..."

That difference is VERY VERY important.

[BrowneIssue]

Presumably 85 people at random?

No. 85 people from the same school.

Sometimes (usually, actually) you are a complete 'tard.

[mudskipper]

No, no, no, no, no.

The classic incorrect question.

"The game show host opens door B, and reveals a goat..." should be:

"The game show host, who knows where the car is, opens another door to intentionally reveal a goat (and never the car)..."

That difference is VERY VERY important.

Yes, indeed. My laziness in cut 'n' pasting the question. The game show host knows where the car is and intentionally reveals the goat.

[cojak]

Quite a good example of baysian statistics, i.e you have a prior probability which you can update with new information to give you a more accurate estimator.

I love the beauty of this stuff, I just don't understand why or how it's beautiful.

I just know it is..