  
18.06.2010, 17:00
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  Re: Ask a Scientist  Quote:      A question if I may...
Why do most economists wear bow ties?
Answers offered via the medium of graphs are trumps.      Because the Wall Street Journal says they are cool and turn women on. 
18.06.2010, 17:14
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  Re: Ask a Scientist  Quote:      Why do most economists wear bow ties?      It's all down to Supply and Demand  practitioners of the Dismal Science demand girlfriends, but the market declines to supply; the bow tie is a valiant ( ) attempt to demonstrate that "Dismal can be Fun, too" Attachment 16342
Last edited by weejeem; 14.10.2011 at 15:03.

18.06.2010, 17:21
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  Re: Ask a Scientist
There are two different classes of bow tie wearer (excluding black tie shenanigans) . . . old school slightly eccentric gentlemen (including economists) and young hipster types . . . there's been a definite trend for the last few years (fading now?). The current Dr Who comes somewhere in between both classes.

24.06.2010, 13:02
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  Re: Ask a Scientist  Quote:      Just got a probability problem,
If you randomly pick 200 figures from 1700, what is the chance of having 5 figures in a row?      This is still bugging me, and seems to be much more difficult to formulate a rigorous answer than first expected
I'm not convinced by the "100%" answer... (sorry, mirfield! )
So, anyone else care to pitch in with a rigorous solution that would conform or refute mirfield's answer?
.

24.06.2010, 13:08
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  Re: Ask a Scientist  Quote:      This is still bugging me, and seems to be much more difficult to formulate a rigorous answer than first expected
I'm not convinced by the "100%" answer... (sorry, mirfield! )
So, anyone else care to pitch in with a rigorous solution that would conform or refute mirfield's answer?
.      This is a pretty straightforward compound probability with replacement, no? If your original pool of 700 remains unchanged after you pick your number, then the probability of picking 5 of the same number is 1/700*1/700*1/700*1/700*1/700. (something like 6x1015).
Now, the fact that your total pool is 700 and you are picking out 200 numbers doesn't change the probability... only how well the actual event will agree with this probability, since you are assuming for probabilistic rules to apply that you are making many many picks.

24.06.2010, 13:09
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  Re: Ask a Scientist  Quote:      This is still bugging me, and seems to be much more difficult to formulate a rigorous answer than first expected
I'm not convinced by the "100%" answer... (sorry, mirfield! )
So, anyone else care to pitch in with a rigorous solution that would conform or refute mirfield's answer?
.      Again, the problem is poorly stated.
First, are the five figures that you pick repeatable (i.e. can I pick, say, 5 twice)?
Second, what is meant by '5 figures in a row'? Do you mean
2,3,4,5,6 or 2,2,2,2,2 (see above)?
try working on a much smaller problem until you understand the issue.
I would suggest doing a little reading on permutations and combinations.

24.06.2010, 13:31
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  Re: Ask a Scientist  Quote:      Just got a probability problem,
If you randomly pick 200 figures from 1700, what is the chance of having 5 figures in a row?      to end the discussion:
wrote small program (labview, yeah !) that does this 1 million times. answer: NEVER !

24.06.2010, 13:41
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  Re: Ask a Scientist  Quote:      to end the discussion:
wrote small program (labview, yeah !) that does this 1 million times. answer: NEVER !      Math proof fail. 
24.06.2010, 13:43
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  Re: Ask a Scientist  Quote:      Again, the problem is poorly stated.
First, are the five figures that you pick repeatable (i.e. can I pick, say, 5 twice)?
Second, what is meant by '5 figures in a row'? Do you mean
2,3,4,5,6 or 2,2,2,2,2 (see above)?
try working on a much smaller problem until you understand the issue.
I would suggest doing a little reading on permutations and combinations.     
Im also confused by the problem explanation

24.06.2010, 13:44
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  Re: Ask a Scientist  Quote:      Math proof fail.      it's the engineers way 
24.06.2010, 13:45
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  Re: Ask a Scientist  Quote:      Again, the problem is poorly stated.
First, are the five figures that you pick repeatable (i.e. can I pick, say, 5 twice)?
Second, what is meant by '5 figures in a row'? Do you mean
2,3,4,5,6 or 2,2,2,2,2 (see above)?
try working on a much smaller problem until you understand the issue.
I would suggest doing a little reading on permutations and combinations.      OK, let's try to tighten it up  Sample, without replacement, 200 numbers randomly from the range 1  700.
 What is the probability, within this sample of 200, of there being at least one "run" of 5 consecutive numbers?
Now, any answers?
.

24.06.2010, 13:45
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  Re: Ask a Scientist  Quote:      it's the engineers way      That's why we are the oompa loompas of science 
24.06.2010, 13:47
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  Re: Ask a Scientist
I have a question relating to sound:
If you take two identical coffee mugs, a jug of boiling water, and a jug of cold water........ Why does temperature affect the sound of pouring water?

24.06.2010, 13:52
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  Re: Ask a Scientist  Quote:      Im also confused by the problem explanation      Imagine I have a bin of 10 balls in a hat, each numbered.
In one experiment, I pick 3 balls, but each time I pick a ball, I put it back in the hat. In this case, My odds of picking any number is 1/10. However, if i do not put any balls back in the hat, the odds for picking any ball change. In this case, for the first ball, I have a 1/10 chance of picking any number, then a 1/9 chance of picking any number, then a 1/8 chance.
Then, I can ask, what are the odds of my picking any 3 number sequence?
I'm assuming that the OP meant picking sequences like 1,2,3 or 4,5,6 and not 2,2,2 or 9,9,9. Now, you have to ask, what are the odds that my 3 numbers make an ordered sequence and not, say, 1,3,9 or 2,4,7. You can also ask what are the odds if the order in which they are chosen matters.
Here, we've assumed that 1,3,9 is the same as choosing 3,1,9 or 1,9,3. What if that's not what we want? 
24.06.2010, 13:54
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  Re: Ask a Scientist  Quote:      I don't know why I thought of this question recently but here goes,
When flying the window shutters need to be open during take off and landing. Why?
I asked a member of the cabin crew when I was last flying but they had no idea. Any insights appreciated      Oh, and I see that this topic has been touched on before, and in cases answered correctly.... But I did study for a commercial helicopter pilots licence and can confirm:
1. Window shutters are open on take off and landing for emergency crews in the event of an accident.
2. Most accidents happen at take off and landing
3. Seatbelts are mostly in place to help identify victums according to the flight manifest.... and reverting back to point 2.
4. That's why you have to stay in your seat for take off and landing.
It sounds a bit morbid, but if the plane goes down and you need to remove any surviving passengers, you need to do this quickly, so you don't want to miss anybody because the shutters are closed.
oh, and one more
5. Cabin crew should know this.
I did just post a question, so I thought I should throw my two cents in.

24.06.2010, 14:03
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  Re: Ask a Scientist
The other thing to look out for is that in reducing your sample size randomly, you will be introducing gaps into your sample space. Thus, you may end up with no groupings of five numbers at all.

24.06.2010, 14:28
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  Re: Ask a Scientist  Quote:      Imagine I have a bin of 10 balls in a hat, each numbered.
In one experiment, I pick 3 balls, but each time I pick a ball, I put it back in the hat. In this case, My odds of picking any number is 1/10. However, if i do not put any balls back in the hat, the odds for picking any ball change. In this case, for the first ball, I have a 1/10 chance of picking any number, then a 1/9 chance of picking any number, then a 1/8 chance.
Then, I can ask, what are the odds of my picking any 3 number sequence?
I'm assuming that the OP meant picking sequences like 1,2,3 or 4,5,6 and not 2,2,2 or 9,9,9. Now, you have to ask, what are the odds that my 3 numbers make an ordered sequence and not, say, 1,3,9 or 2,4,7. You can also ask what are the odds if the order in which they are chosen matters.
Here, we've assumed that 1,3,9 is the same as choosing 3,1,9 or 1,9,3. What if that's not what we want?      I got asked the following once (I'm no math nerd, but people make assumptions when you're a programmer).
What are the chances of the lottery numbers being sequential? Arguing that there's no point in ever picking sequential numbers for your ticket as it's much more likely that non sequential numbers would appear. I thought that in the long run, any set of numbers would have exactly the same chance of winning, sequential or not, as each combination of numbers is equally unlikely to win you the jackpot.

24.06.2010, 14:31
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  Re: Ask a Scientist  Quote:      2. Most accidents happen at take off and landing
.      Well technically, all accidents happen at landing
billhardie: Obviously the highly excited state of the boiling water changes the sound wave that comes off the mug. How different is the sound though?

24.06.2010, 14:49
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  Re: Ask a Scientist  Quote:      Well technically, all accidents happen at landing
billhardie: Obviously the highly excited state of the boiling water changes the sound wave that comes off the mug. How different is the sound though?      The sound is 'deeper' with boiling water. Cold water has a higher pitch. It's a bit difficult to describe the sound in words.
It's just something I notice, and have always wondered about.
Oh, and for accidents excluding Take off and Landing, I was reffering to Mid air collisions, Mountains, Cabin pressure, Mechanical failure, etc..... things that go wrong during flight, but right you are, they all end up in the same place.

24.06.2010, 19:36
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  Re: Ask a Scientist  Quote:      I got asked the following once (I'm no math nerd, but people make assumptions when you're a programmer).
What are the chances of the lottery numbers being sequential? Arguing that there's no point in ever picking sequential numbers for your ticket as it's much more likely that non sequential numbers would appear. I thought that in the long run, any set of numbers would have exactly the same chance of winning, sequential or not, as each combination of numbers is equally unlikely to win you the jackpot.      The explanation I've heard before is that all combinations are equally likely, but you are likely to win less because lots* of people choose sequential numbers. * Yes, I know, but "lots" is as good an estimate as I can guess. 
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