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October 23, 2025, 10:22:50 am

Author Topic: TT's Maths Thread  (Read 149536 times)  Share 

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the.watchman

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Re: TT's Maths Thread
« Reply #975 on: May 04, 2010, 09:07:03 pm »
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Ah but you know that one of the other doors is a goat, right?
So in each case it is a question of 50:50, but in the overall scheme, the three cases yield a 2/3 chance IF you switch :)

I love this question, don't you TT and brightsky? :D
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TrueTears

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Re: TT's Maths Thread
« Reply #976 on: May 04, 2010, 09:09:59 pm »
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no i dont like probability.

anyways i dont get it...

"If you pick door B and you switch, you'll get the car."

u dont tho, u can pick the goat still

So if you pick door C first, you have a probability of 1 of picking the goat if u switch, so u lose, so why would u wanna switch here?

But the answer is switching is always better, but clearly here, if u switch ur gonna lose instead of win
« Last Edit: May 04, 2010, 09:13:41 pm by TrueTears »
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kamil9876

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Re: TT's Maths Thread
« Reply #977 on: May 04, 2010, 09:22:21 pm »
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What if the host himself does not know where the car is, and may accidentally remove it. what should you do?
Voltaire: "There is an astonishing imagination even in the science of mathematics ... We repeat, there is far more imagination in the head of Archimedes than in that of Homer."

the.watchman

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Re: TT's Maths Thread
« Reply #978 on: May 04, 2010, 09:24:07 pm »
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After an overall view of all cases, it is obvious that switching is better in general
Oh, and with the pick door B case, you are shown that one of the doors (A in this case) has a goat behind it, so if you switch you will pick C which has the car etc.

What if the host himself does not know where the car is, and may accidentally remove it. what should you do?

Lol, not gonna happen... :D
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TrueTears

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Re: TT's Maths Thread
« Reply #979 on: May 04, 2010, 09:25:44 pm »
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ahhh i don't care anymore, dont get this Q, dont care either now
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brightsky

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Re: TT's Maths Thread
« Reply #980 on: May 04, 2010, 09:34:49 pm »
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Quote
"If you pick door B and you switch, you'll get the car."

u dont tho, u can pick the goat still

So if you pick door C first, you have a probability of 1 of picking the goat if u switch, so u lose, so why would u wanna switch here?

The other door is already open. So you know what's in one door already, the only options are to stick with door B or switch to whatever door isn't open.

Again, picking door C is the only case where when you switch you don't get the car. In the remaining two cases, you do get the car if you switch.



And yes I do hate probability...and statistics too. xD
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TrueTears

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Re: TT's Maths Thread
« Reply #981 on: May 04, 2010, 09:36:30 pm »
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OMFG

I READ THE FUKN QUESTION WRONG, LOL I THOUGHT THE HOST DOESNT OPEN ANY DOORS AFTER U PICK UR DOOR, I THOUGHT HE'D JUST ASK U IF U WANNA SWITCH TO EITHER OF THE 2 OTHER DOORS


OMFG


FKN.........

shit shit no wonder, yeah i get it now totally lolololol epic fail ><
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the.watchman

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Re: TT's Maths Thread
« Reply #982 on: May 04, 2010, 09:41:17 pm »
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OMFG

I READ THE FUKN QUESTION WRONG, LOL I THOUGHT THE HOST DOESNT OPEN ANY DOORS AFTER U PICK UR DOOR, I THOUGHT HE'D JUST ASK U IF U WANNA SWITCH TO EITHER OF THE 2 OTHER DOORS


OMFG


FKN.........

shit shit no wonder, yeah i get it now totally lolololol epic fail ><

Lol, it is trippy though... :)
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Yitzi_K

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Re: TT's Maths Thread
« Reply #983 on: May 04, 2010, 10:20:34 pm »
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It's counter intuitive, but it is better to switch. There's an iPhone app which runs simulations of this scenario, and if you switch, the likelihood of getting the car is 66.67%
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Re: TT's Maths Thread
« Reply #984 on: May 04, 2010, 11:50:03 pm »
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I think this is called the Monty Hall problem

TrueTears

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Re: TT's Maths Thread
« Reply #985 on: May 04, 2010, 11:53:21 pm »
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yeah it is, kamil just told me on msn, also showed me a neat tree diagram which explains it instantly
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Ahmad

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Re: TT's Maths Thread
« Reply #986 on: May 10, 2010, 11:11:26 pm »
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Probability is awesome.
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Re: TT's Maths Thread
« Reply #987 on: June 27, 2010, 04:32:49 am »
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Find the Taylor series for centered around .

I've gotten pretty close but I don't know how to put it back into summation format. This is my working:











So we have:



So I know the summation form must have but I can't find the pattern for

Help please, thanks!
« Last Edit: June 27, 2010, 04:39:22 am by TrueTears »
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googoo

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Re: TT's Maths Thread
« Reply #988 on: June 27, 2010, 08:46:13 am »
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To me it is so simple. There is a greater chance (2/3) of picking the goat at the first pick. If you are given a second chance to switch, why not.

Damo17

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Re: TT's Maths Thread
« Reply #989 on: June 27, 2010, 09:53:55 am »
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Find the Taylor series for centered around .

I've gotten pretty close but I don't know how to put it back into summation format. This is my working:











So we have:



So I know the summation form must have but I can't find the pattern for

Help please, thanks!


Notice that the numerators starting from the term are like the factorials we normally see with an odd positive integer multiplied by all the odd positive integers down to 1.

From Wikipedia:
Quote
A function related to the factorial is the product of all odd values up to some odd positive integer n. It is often called double factorial (even though it only involves about half the factors of the ordinary factorial, and its value is therefore closer to the square root of the factorial), and denoted by n!!.

So we get as part of the summation:



But this is only for . So the full summation form is:


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