How smart are you MPs?

hhiusa

Senior member
2,687 139
Quarter, isn't that somewhere near "the iraq"?

??? Quarter and Iraq.:confused: That is an interesting segue or lack thereof as the case is here.

I will make a segue for you.

Qatar is not that close to Iraq. That is like saying London, isn't that somewhere near Denmark? London to the border of Denmark is about the same distance that Qatar is from the border of Iraq.
 
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tomorton

Legendary member
8,040 1,180
Says the man who doesn't know what a quarter is. :LOL:

Well nobody answered my question what's a quarter. Maybe they don't know either.

But anyway, happy you don't disagree with the main point - the more valuable the coin, the more probabible you will lose any competition based on probabibility. Its just like when you get a puncture - it will only ever be when you need to be somewhere in a hurry and that's another well known fact.
 

darktone

Veteren member
3,985 1,040
Well nobody answered my question what's a quarter. Maybe they don't know either.
Sorry Tom. As I understand it a quarter is most likely to mean 25%, or a fourth.
As in:-
The very smart man only knew 25% of knowledge and smartness of wot he thought he knew. There fourth being desperate to impress, he took the other two thirds in partials at 70% stakes of total knowledge at key times in history when he went back to the past.

I could be wrong mind.
 

hhiusa

Senior member
2,687 139
Well nobody answered my question what's a quarter. Maybe they don't know either.

But anyway, happy you don't disagree with the main point - the more valuable the coin, the more probabible you will lose any competition based on probabibility. Its just like when you get a puncture - it will only ever be when you need to be somewhere in a hurry and that's another well known fact.
A quarter is a quarter dollar. One side has George Washington's face called "heads", the other side has the presidential coat of arms called "tails". The original question is about flipping two quarters and both of them coming up "heads". The answer is 1/4. The probability of two events occuring together is the product of their probabilities.
 

alexaherself

Established member
560 149
Talking of quarters (and who isn't, these days?) ...

... if one coin (A) is weighted so that it comes up heads a quarter of the time, and another (B) weighted so that it comes up heads three quarters of the time, and one of the coins - randomly selected - is flipped twice with both outcomes being "heads", then what was the probability that it was coin B that was flipped?
 

alexaherself

Established member
560 149
Would you also have said 50% if the parameters in the question had been that one coin were weighted to come up heads 99% of the time, and the other to come up heads 1% of the time, Tim? :sneaky:
 

timsk

Legendary member
7,304 2,089
Would you also have said 50% if the parameters in the question had been that one coin were weighted to come up heads 99% of the time, and the other to come up heads 1% of the time, Tim? :sneaky:
Yes. The weightings and the number of times the selected coin is flipped are red herrings. It's the (random) selection of the coin in the first place that the question relates to which, as there's just two coins, is a straight 50:50 proposition. I think!
:cool:
 

alexaherself

Established member
560 149
Would you also have said 50% if the parameters in the question had been that one coin were weighted to come up heads 99% of the time, and the other to come up heads 1% of the time, Tim? :sneaky:
Yes.
Ouch ... I admit I was asking rhetorically, by way of saying "You couldn't possibly think that ..."? :eek:

The weightings and the number of times the selected coin is flipped are red herrings. It's the (random) selection of the coin in the first place that the question relates to which, as there's just two coins, is a straight 50:50 proposition. I think!
Er, no ... apologies if the context misled you, guys ... it's not a "trick question". It's a non-trivial probability question ...

Noooooo ... I should have said, in asking the question, something like "By the way, this is a more difficult and complicated question than it appears" ... :sneaky:
 

alexaherself

Established member
560 149
If it puts the question in a better and more appropriate context, you might want to see where I stole it from. The heading and very last question of this little pdf explain further: http://www.maths.cam.ac.uk/sites/www.maths.cam.ac.uk/files/pre2014/undergrad/pastpapers/2015/ia/PaperIA_2.pdf :eek: :cheesy:

I just happened to be looking at this year's papers, a couple of nights ago (I look at these, each year, when they're published online :eek: ), and the word "quarter" just stuck in my mind.

I do have an answer. It's only my own answer (I haven't checked it with an examiner, or anything) but I think it's right, and it isn't 50% or 75%. :|
 
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