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Mathematics

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gruff5
1155400.  Sun Oct 25, 2015 7:13 pm Reply with quote

Well, what you say makes perfect sense, WL.

Amongst the (many) lengthy discussions on 0.999 ... here and even more so, elsewhere, a lot of folks were arguing the that the notion of limit had been superseded in the "..." notation.

 
gruff5
1155826.  Wed Oct 28, 2015 3:54 am Reply with quote

BTW that James Meyer book seems to do a reasonable job at showing the failing of Cantor's diagonal number "proof". Though I'm not a mathematician, so can't really judge. It's only 1.16 on Amazon kindle.

 
Prof Wind Up Merchant
1161274.  Fri Dec 04, 2015 3:29 pm Reply with quote

The limerick about the mathematical equation was awesome. I do not know if it was an unintended consequence or a deliberate construction.

http://poetrywithmathematics.blogspot.co.uk/2010/03/mathematical-limericks.html

 
AlmondFacialBar
1199293.  Wed Jul 20, 2016 7:34 am Reply with quote

bemahan wrote:
This reminds me of confusion that arises with parents with a faulty gene. They are told (say) that one in four of children* will have the faulty gene. The parents take that to mean that if their first child has the faulty gene then the next 3 won't have it. :(

Edited because the way I originally worded it would definitely cause that exact confusion!


In fairness, the chance of the other three not having it is slightly lower, though definitely not eliminated. Happy version of that one - an acquaintance of mine carries a gene for a life-limiting X-linked condition and... Has two healthy boys. Anyone care to work out what the chances of that are?

(Before someone starts on irresponsible behaviour - she received her diagnosis after the birth of the first one and the second one is the much loved result of a pill failure.)

:-)

AlmondFacialBar

 
PDR
1199294.  Wed Jul 20, 2016 7:43 am Reply with quote

AlmondFacialBar wrote:

In fairness, the chance of the other three not having it is slightly lower, though definitely not eliminated.


Is it?

If so I presume it's for some clinical rather than statistical reason!

PDR

 
AlmondFacialBar
1199328.  Wed Jul 20, 2016 11:24 am Reply with quote

Hm... I might be getting my Maths wrong there in fairness. Could you elaborate?

:-)

AlmondFacialBar

 
Zziggy
1199329.  Wed Jul 20, 2016 11:39 am Reply with quote

They are independent events. Having a child with a genetic problem doesn't reduce the chances of the next one having it, any more than fipping a coin and having it come up heads means it's more likely that the next time you flip it you'll get a tails.

 
PDR
1199330.  Wed Jul 20, 2016 11:55 am Reply with quote

AlmondFacialBar wrote:
Hm... I might be getting my Maths wrong there in fairness. Could you elaborate?


My quibble would be that you appeared to be suggesting the genetic dice had a memory, so the dice falling one way with the first child would influence the probability that they would fall the same way with subsequent children.

From a purely statistical perspective this wouldn't be true - the possible outcomes have the same probabilities every time the genetic dice are ejected.

But I wondered if there might be clinical reasons why the first outcome might influence subsequent ones - there are several physical conditions which are less likely after the first child because the manufacturing and delivery equipment is "run in" by birth of the first. But in the ansence of that kind of mechanism I think your point could have been incorrect.

PDR

 
AlmondFacialBar
1199360.  Wed Jul 20, 2016 3:59 pm Reply with quote

Zziggy wrote:
They are independent events. Having a child with a genetic problem doesn't reduce the chances of the next one having it, any more than fipping a coin and having it come up heads means it's more likely that the next time you flip it you'll get a tails.


You are of course perfectly correct. And that's why I shouldn't post Maths related things from the hip between two meetings.

:-)

AlmondFacialBar

 
PDR
1199382.  Wed Jul 20, 2016 5:42 pm Reply with quote

...which just forces me to ask why you have a hip between two meetings. Is it some local custom, or an old and tired joke (like the large fluffy toy elephant I had in one corner of my office during the brief period I actually had an office to myself).

PDR

 
gruff5
1204518.  Sun Sep 11, 2016 10:47 pm Reply with quote

I'm on a 1Kb/s connection here (not exaggerating - Philippines) & can't see images, but there's a algebra puzzle in The Mirror that other media outlets are claiming is "baffling the internet":

http://www.mirror.co.uk/news/world-news/simple-horse-algebra-question-left-8781091

I suspect (without seeing it) that the "bafflement" is purely because horses etc are used, rather than x, y & z?

 
PDR
1204531.  Mon Sep 12, 2016 4:27 am Reply with quote

There is a typo in the final line of their worked solution which renders it incorrect, which doesn't help.

Essentially the three symbol are horse, horseshoe and boot. The first three lines are (the brackets here are mine, based on the way the picture is shown):

Horse + Horse + Horse = 30
Horse + (two horseshoes) + (2 horseshoes) = 18
(Two horseshoes) - (two boots) = 2

These establish that the values of the three are:

Horse = 10
Horseshoe = 2
Boot = 1

They then have a final line that says:

Boot + Horse x horseshoe = ??

[in the worked example this has been transcribed to "Boot + Horse + horseshoe = ??
" which would of course have no arguments]

So that's:

1 + 10 x 2 = ??

What people are arguing about is whether this should be

(1+10) x 2 = 22

or

1 + (10x2) = 21

This is just a notation convention issue which I'll leave to the reader.

PDR

 
gruff5
1204779.  Wed Sep 14, 2016 3:41 am Reply with quote

Ah, OK, I think the Mirror article referenced a rule for arithmetic expansion (MOMA? or is that an art gallery?!)

 
PDR
1204787.  Wed Sep 14, 2016 4:32 am Reply with quote

Did they mention "BODMAS" (the convention on the order of priority in algebra statements without parentheses)?

PDR

 
gruff5
1204885.  Thu Sep 15, 2016 4:20 am Reply with quote

yes, think it was BODMAS - sorry, I was too lazy to refer back to the article.

 

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