Page 12 of 43 FirstFirst ... 2101112131422 ... LastLast
Results 166 to 180 of 645

Thread: The Maths Thread

  1. #166
    International 12th Man blahblahblah's Avatar
    Join Date
    Jun 2010
    Location
    As always, my room
    Posts
    1,731
    Quote Originally Posted by vcs View Post
    LOL, that's an old one. North Pole, polar bear.
    how did u get that?
    Last edited by blahblahblah; 11-10-2010 at 10:53 PM.

  2. #167
    International Captain cover drive man's Avatar
    Join Date
    Dec 2006
    Location
    Liverpool, England
    Posts
    7,139
    Quote Originally Posted by blahblahblah View Post

    On one particularly steamy summer day, nine women break their vows with other men. What is the result?
    Where the women members of the community?
    Everyone wants to change the world, noone wants to change himself.

    -Tolstoy

  3. #168
    International 12th Man blahblahblah's Avatar
    Join Date
    Jun 2010
    Location
    As always, my room
    Posts
    1,731
    Quote Originally Posted by cover drive man View Post
    Where the women members of the community?
    yep all 9 belonged to that community

  4. #169
    International 12th Man blahblahblah's Avatar
    Join Date
    Jun 2010
    Location
    As always, my room
    Posts
    1,731
    Quote Originally Posted by blahblahblah View Post
    2 brain teasers i found interesting

    1)

    Okay, so a hunter gets out of his cabin on morning and gets into his jet powered surface cruiser. He travels 4000 miles south; turns eastward and travels 4000 miles and finally turns north and cruises for 4000 miles, at the end of which he is back outside his cabin. Now he sees a bear standing outside his kitchen window and eyeing the pie he had left to cool.

    What is the color of the bear ?

    Give complete solution, with reasoning !
    correct solution:

    First, where is the hunter? Either at the North pole, or at any line of latitude such that, if you go 4000 miles south, you reach a line of latitude whose length times some natural number is 4000 miles. And when I talk about the length of the line of latitude, I mean the circumference of the cross-section of the Earth at that latitude.

    If the hunter's at the north pole, the bear is probably white-looking (a polar bear). If that's not where he is, then the bear might be brownish, blackish, or greyish; those are the only other colours I can think that bears are found in, and I think there are enough places in the world that the hunter could be so that the bear might be any one of those colours.


    If you travel 4000 miles south you are down around the 60 degree north line of latitude. The length of this line is about 12000 miles. The line of latitude that is 4000 miles is about 80 degrees north. Since this is well within 4000 miles of the north pole, you can't go 4000 miles south to get to it. This means that the cabin is at the north pole.

    This makes the bear orange. Since no polar bears live that far north, and, as I recall, a wealthy prankster who hated this joke mounted an expedition to the pole to place the orange-dyed, frozen carcass of a bear at the exact pole.

    By Njorl


  5. #170
    International Coach PhoenixFire's Avatar
    Curveball Champion!
    Join Date
    Sep 2006
    Location
    Bitch please, I'm from West Yorkshire
    Posts
    14,988
    Can anyone fathom where I've gone wrong here?

    (CosecX)^2 + CotX - 2 = 0

    1/(SinX)^2 + 1/TanX - 2 = 0

    SinX/(Sinx)^2 + SinX/TanX - 2SinX = 0

    SinX + CosX - 2Sinx = 0

    CosX - SinX = 0

    And solve from there. I've done that, but the answer is different to the one in the book..
    Quote Originally Posted by Top_Cat View Post
    1) Had double pneumonia as a kid, as did my twin sis. Doctors told my parents to pray that we lived through the night. Dad said **** off, I'm an atheist, you ****s better save my kids, etc. Then prayed anyway.

  6. #171
    Hall of Fame Member Marcuss's Avatar
    Join Date
    Feb 2009
    Location
    Above you
    Posts
    15,597
    Quote Originally Posted by PhoenixFire View Post
    Can anyone fathom where I've gone wrong here?

    (CosecX)^2 + CotX - 2 = 0

    1/(SinX)^2 + 1/TanX - 2 = 0

    SinX/(Sinx)^2 + SinX/TanX - 2SinX = 0

    SinX + CosX - 2Sinx = 0

    CosX - SinX = 0

    And solve from there. I've done that, but the answer is different to the one in the book..

  7. #172
    International 12th Man blahblahblah's Avatar
    Join Date
    Jun 2010
    Location
    As always, my room
    Posts
    1,731
    yup

    sinx/(sinx)^2=1/sinx

    but u have taken it as sinx

  8. #173
    International Coach PhoenixFire's Avatar
    Curveball Champion!
    Join Date
    Sep 2006
    Location
    Bitch please, I'm from West Yorkshire
    Posts
    14,988
    Duh.

    Chrz guys.

  9. #174
    International 12th Man blahblahblah's Avatar
    Join Date
    Jun 2010
    Location
    As always, my room
    Posts
    1,731
    anyone here who has been in australia and been to terence tao`s classes or lectures anytime?

  10. #175
    International Vice-Captain Redbacks's Avatar
    Join Date
    Mar 2008
    Location
    NT
    Posts
    4,169
    Quote Originally Posted by blahblahblah View Post
    2)

    A Hungarian community of married mathematicians has the following tradition: should any man determine that his wife cheated on him, he shall hang himself at noon. The townsfolk being rather introverted, there is little gossip except when there is an affair. In such case everyone in the town hears about the infidelity by nightfall excepting, of course, the cheating couple's spouses. So if a man were to hear gossip but were not told of any affiar, he would determine, being the logical mathematician that he is, that his own wife was involved, and would thus hang himself at noon the next day.

    On one particularly steamy summer day, nine women break their vows with other men. What is the result?
    They hang on the 9th day.

    For the case that there is only one affair, it has to be known that there has been an affair by all members of the community otherwise the individual has no means of determining that a lack of knowledge of any other affairs results in him being the one.
    Let k=2 for the number of affairs: then by the second day, it is common knowledge by both men that: initially they both knew of at least 1 other affair, as a result of the other not killing themselves, each of them must have known of another affair, by the second day, they can reason that it was them and the other they know of.
    k=3. Let a,b and c be the cheated on men. At day 2, following from k=2, a assumes that 'had he not been cheated on', then b and c would have by the case k=2, killed themselves on the 2nd day. Thus a was also cheated on.
    .
    .
    .
    This follows in our case (for k=9) that by day 8, each of the nine men know of 8 other affairs and by induction know that; had they not also been a victim, the other 8 men would have known of only 7 victims, and by induction all hung themselves on the 8th day. Finally on the 9th day it's common knowledge than 9 men have been cheated on so they all hang themselves.
    Last edited by Redbacks; 07-11-2010 at 12:41 AM. Reason: poor wording.... :(

  11. #176
    International 12th Man blahblahblah's Avatar
    Join Date
    Jun 2010
    Location
    As always, my room
    Posts
    1,731
    cool stuff redbacks..

    u got any problems u willing to share?

    u r welcome =)

  12. #177
    Cricket Web: All-Time Legend Top_Cat's Avatar
    Join Date
    Feb 2002
    Location
    Adelaide, South Australia
    Posts
    23,158
    Tangentially maths-related but anyone got any experience in using Bayesian stats and SEM in their research? Been mulling over introducing it to existing and new projects here but I work mostly with psychologists so if doesn't resemble SPSS output, they freak out. Running my models in R so the fact you actually have to type commands is too much already.

    Looking for experiences in terms of whether they were more likely to get their papers up in a good journal, whether you got results which made more sense, clearer conclusions, etc. It's yet to really catch on here but I know both R and Bayes are the new black over in the US right now.
    Last edited by Top_Cat; 15-11-2010 at 08:23 PM.
    The Colourphonics

    Bandcamp
    Twitderp

  13. #178
    International 12th Man Quaggas's Avatar
    Join Date
    Jun 2009
    Location
    USA
    Posts
    1,683
    Quote Originally Posted by Top_Cat View Post
    Tangentially maths-related but anyone got any experience in using Bayesian stats and SEM in their research? Been mulling over introducing it to existing and new projects here but I work mostly with psychologists so if doesn't resemble SPSS output, they freak out. Running my models in R so the fact you actually have to type commands is too much already.

    Looking for experiences in terms of whether they were more likely to get their papers up in a good journal, whether you got results which made more sense, clearer conclusions, etc. It's yet to really catch on here but I know both R and Bayes are the new black over in the US right now.
    Speaking from Eco/Fin background: I have never seen a situation where the software used is relevant to the quality of a paper. My suspicion is that if the paper goes on about the econometric technology/software used, it's likely garbage anyway because the authors don't really know what they're doing. Of course, in the unlikely event that it's a question of some esoteric function not available in one or the other software, it's a different matter (or write own routine). R is very useful, I think, but it's just a tool, as are stata, eviews, matlab, C, etc

    Bayesian stats is an odd one. I know quite a few economists that think it's "overrated," but I think that comment is more often that not specific to the paper's idea as a whole, not the method. It's seductive to think one has stumbled across something significant because one can cite a bunch of statistics, but in the end what matters is what the data brings to an interesting conjecture.... for example, lots of papers are written about mass valuation tools for housing prices, using NN, vector support machines, etc, but they're generally useful only for a practitioner planning to go IPO, not for publication in a serious journal. They tend to rehash established models and are useless from the point of view of furthering knowledge - who the heck cares if prices are not actually linear in number of bathrooms in some suburb of Atlanta. Typically, people have some access to an oddball data set and try their mightiest to publish by spinning it through the washer w/o bothering to think too hard about what might be going on. Editors tend to give such papers to junior faculty like me to reject; it's a pain in the *** but comes with the territory.

    BTW, I'd change collaborators if they're that stuck on SPSS! Just my 2cents.
    Last edited by Quaggas; 15-11-2010 at 09:48 PM.

  14. #179
    Cricket Web: All-Time Legend Top_Cat's Avatar
    Join Date
    Feb 2002
    Location
    Adelaide, South Australia
    Posts
    23,158
    I see your point but I do think those who characterise themselves as either Bayesian or frequentist do over-rate Bayes a bit. It's a tool, not a religion and there's room for either/both/all depending on the context.

    Just seems like something I should get some work here with, I guess. I saw a stats job for Google, both Bayes and R were mentioned as essential and it's popping up more in research spots here. That said, I do think they're looking more for IT types who can sort-of understand stats rather than a statistician who programs, if you know what I mean. Stats is sort of looked at as a formality; as long as your QQ's look right and p < .05, all good. If they don't, transpose the data until they do; don't, for the love of god, ask questions about your sampling methodology or whether your data might be ****.

  15. #180
    Hall of Fame Member Howe_zat's Avatar
    Join Date
    Nov 2010
    Location
    Top floor, bottom buzzer
    Posts
    16,426
    Can I just say how much I love that this thread exists?

    You guys are the best.
    Every 5 years we have an election and have to decide who are the least obnoxious out of all the men. Then one gets in and they age really quickly. Which is always fun to watch.

Page 12 of 43 FirstFirst ... 2101112131422 ... LastLast


Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Tech Geeks Thread
    By SupaFreak2005 in forum Off Topic
    Replies: 233
    Last Post: 03-11-2012, 03:15 PM
  2. *Nikhil Hearing* Details Thread
    By lord_of_darkness in forum Cricket Web XI
    Replies: 329
    Last Post: 17-12-2004, 03:21 PM
  3. **Official** South Africa in India Thread
    By Neil Pickup in forum Cricket Chat
    Replies: 453
    Last Post: 08-12-2004, 07:26 AM
  4. *Official* India in Australia Thread
    By Craig in forum Cricket Chat
    Replies: 2652
    Last Post: 08-01-2004, 07:00 PM
  5. *Official* West Indies in Zimbabwe Thread
    By Mr Mxyzptlk in forum Cricket Chat
    Replies: 554
    Last Post: 01-12-2003, 03:11 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •