Three bags are marked $10, $15, and $20. One bag contains two $5 dollar bills, one contains a $5 and a $10 bill, and one contains two $10 bills. You are told that no bag contains the amount of money that is marked on its exterior. You are allowed to select a bag and extract a bill. How many times must you do this before before you can guarantee that you know the contents of all three bags? What is your strategy?
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Money Bags
26 January 2013 - 11:03 PM
Colored Cards
26 January 2013 - 10:55 PM
A bag contains three cards, one blue on both sides, one green on both sides, and one with one blue side and one with one green side. You pull one card from the bag and place it on the table. The side showing is blue. What is the probability that the side not showing is also blue?
Job Interview
25 October 2012 - 05:52 AM
At a job interview, your potential employer presents you with the following test:
There are 2 buckets, and a bin with 50 green balls and 50 red balls.
He tells you he will leave the room, and that you must place the balls in the buckets.
When he comes back, he will randomly select a bucket (with equal probability), and randomly draw a ball from that bucket.
If he draws a green ball, you are hired.
Rules:
I. No bucket can be empty
II. Each of the 100 balls must be placed in one of the two buckets
What do you do?
There are 2 buckets, and a bin with 50 green balls and 50 red balls.
He tells you he will leave the room, and that you must place the balls in the buckets.
When he comes back, he will randomly select a bucket (with equal probability), and randomly draw a ball from that bucket.
If he draws a green ball, you are hired.
Rules:
I. No bucket can be empty
II. Each of the 100 balls must be placed in one of the two buckets
What do you do?
Recursion
21 October 2012 - 10:43 AM
Find a closed-form expression for F(a,b) where:
F(a,b) = F(a-1,b) + F(a-1,b-1),
F(a,0) = 1 for all a
F(0,b) = 0 for all b
a and b are positive integers
F(a,b) = F(a-1,b) + F(a-1,b-1),
F(a,0) = 1 for all a
F(0,b) = 0 for all b
a and b are positive integers
Captain's Conundrum
21 September 2012 - 05:52 AM
A captain hires a crew for his ship, "The Flying Scotsman" and sets out to sail for a voyage to last many years across the seven seas.
As the years pass, The Flying Scotsman succumbs to wear and tear:
In the Atlantic ocean, the ship's mast is blown away by a storm, and it is replaced in the Caribbean.
In the Pacific ocean, the ship runs aground and the hull is severely damaged. Fortunately, they are able to hire natives to aid in the repairs.
...etc
After 8 long years, the captain looks at his beloved "Scotsman", and thinks fondly of how it has served him, he has a realization: over the course of this grand adventure, every piece of The Flying Scotsman has been replaced due to wear and tear.
The captain begins to feel uncomfortable.... if I'm standing on different wood.... aren't I standing on a different ship?
Question:
Is it the same ship?
The captain fainted from philosophical exhaustion.
As the years pass, The Flying Scotsman succumbs to wear and tear:
In the Atlantic ocean, the ship's mast is blown away by a storm, and it is replaced in the Caribbean.
In the Pacific ocean, the ship runs aground and the hull is severely damaged. Fortunately, they are able to hire natives to aid in the repairs.
...etc
After 8 long years, the captain looks at his beloved "Scotsman", and thinks fondly of how it has served him, he has a realization: over the course of this grand adventure, every piece of The Flying Scotsman has been replaced due to wear and tear.
The captain begins to feel uncomfortable.... if I'm standing on different wood.... aren't I standing on a different ship?
Question:
Is it the same ship?
Spoiler for If so
So what (materials/subcomponents) things are made of doesn't matter when considering identity?
Would this even apply if we were talking about you and not a ship?
What if you stepped into a teleporter that disassembled all of your atoms, transmitted the information through space to a habitable facility on Mars and re-assembled you using atoms from Mars ?
Would that still be you?
What if the teleporter malfunctioned, and after you were disassembled, both devices on Earth and on Mars re-assembled you so that there are two copies of you.
Which one is the real you? Do they have separate identities or are they same?
What properties of these perfect clones could you use to distinguish their identities?
Could such properties be used to distinguish every possible pair of arbitrary things that anyone might claim to be identical?
What about applying those properties to distinguish yourself now to one moment ago?
If everything can be distinguished, does true sameness exist?
If every possible thing is different, should we really be so attached to our common ideas of objects?
If you have a cup on a table, where does the cup end and the table begin? Would it be wrong to consider them both as part of a single object, let's call it a cup-table. Is the concept of a cup-table more or less in tune with reality (outside of our own subjective perspectives) than that of a cup by itself, or a table by itself?
If we can call anything we want an object, is there any fundamental meaning to the concept of objects outside of a subjective perspective?
Stepping outside of human subjective perspectives (pretend that we can), is there any objective basis for defining anything around us as objects outside of our own subjective perspectives .... is that object I'm looking at a cup on my table, or is it a cup-table, or a cup-table-atmosphere-house-earth-space-universe?
In essence, do objects (e.g. cup, horse, car), as we know them, actually exist outside of our minds?
Would this even apply if we were talking about you and not a ship?
What if you stepped into a teleporter that disassembled all of your atoms, transmitted the information through space to a habitable facility on Mars and re-assembled you using atoms from Mars ?
Would that still be you?
What if the teleporter malfunctioned, and after you were disassembled, both devices on Earth and on Mars re-assembled you so that there are two copies of you.
Which one is the real you? Do they have separate identities or are they same?
What properties of these perfect clones could you use to distinguish their identities?
Could such properties be used to distinguish every possible pair of arbitrary things that anyone might claim to be identical?
What about applying those properties to distinguish yourself now to one moment ago?
If everything can be distinguished, does true sameness exist?
If every possible thing is different, should we really be so attached to our common ideas of objects?
If you have a cup on a table, where does the cup end and the table begin? Would it be wrong to consider them both as part of a single object, let's call it a cup-table. Is the concept of a cup-table more or less in tune with reality (outside of our own subjective perspectives) than that of a cup by itself, or a table by itself?
If we can call anything we want an object, is there any fundamental meaning to the concept of objects outside of a subjective perspective?
Stepping outside of human subjective perspectives (pretend that we can), is there any objective basis for defining anything around us as objects outside of our own subjective perspectives .... is that object I'm looking at a cup on my table, or is it a cup-table, or a cup-table-atmosphere-house-earth-space-universe?
In essence, do objects (e.g. cup, horse, car), as we know them, actually exist outside of our minds?
Spoiler for If not
When did it stop being the same ship? Was it when the mast blew over?
What if the wood is constantly interacting with the air and water around it, such that sometimes, wood particles fly off of the ship, and air/water particles get stuck in the wood. This is all completely undetectable to unaided senses. Suppose this started happening from the moment the ship was exposed to the elements forward.
Is it a different ship whenever such a particle transfer occurs?
What about you?
Are you a different person in each moment as you age?
Can two objects ever truly be the same?
If not, does this mean sameness does not exist?
Is it an arbitrary judgment to even define things as objects? Where does the ship end and the water begin?
What if you thought that the Ship+Water was actually a single object, let's call it ship-water. This object includes all the atoms of both the ship and water together. Is it justifiable to call this an object?
Stepping outside of human subjective perspectives (pretend that we can), is there any objective basis for defining anything around us as objects outside of our own subjective perspectives .... is that object I'm looking at a cup on my table, or is it a cup-table, or a cup-table-atmosphere-house-earth-space-universe?
In essence, do objects (e.g. cup, horse, car), as we know them, actually exist outside of our minds?
When did it stop being the same ship? Was it when the mast blew over?
What if the wood is constantly interacting with the air and water around it, such that sometimes, wood particles fly off of the ship, and air/water particles get stuck in the wood. This is all completely undetectable to unaided senses. Suppose this started happening from the moment the ship was exposed to the elements forward.
Is it a different ship whenever such a particle transfer occurs?
What about you?
Are you a different person in each moment as you age?
Can two objects ever truly be the same?
If not, does this mean sameness does not exist?
Is it an arbitrary judgment to even define things as objects? Where does the ship end and the water begin?
What if you thought that the Ship+Water was actually a single object, let's call it ship-water. This object includes all the atoms of both the ship and water together. Is it justifiable to call this an object?
Stepping outside of human subjective perspectives (pretend that we can), is there any objective basis for defining anything around us as objects outside of our own subjective perspectives .... is that object I'm looking at a cup on my table, or is it a cup-table, or a cup-table-atmosphere-house-earth-space-universe?
In essence, do objects (e.g. cup, horse, car), as we know them, actually exist outside of our minds?
The captain fainted from philosophical exhaustion.
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