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Mathematical riddles


kolko

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After seeing the popularity of the 0.99... equals 1 topic, I figured this would go well too. This is a topic about mathematical riddles ::'

 

 

 

My riddle:

 

 

 

You have a race car that completes half of a certain distance with an average speed of 60mph.

 

How fast would it have to average on the second half to bring its total average to 120mph?

 

 

 

Do not go for the obvious answer, think logically :)

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I warned you not to go for the obvious answer ;)

 

 

 

[hide=]Let's say the distance is 120 miles. The car goes at 60 mph so it takes an hour for the first half. If you go the second half at 180 miles per hour, you do the next 60 miles in 20 minutes. In total, you do 1 hour and 20 minutes over 120 miles which is 90 miles per hour.[/hide]

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[hide=]no matter how fast it goes over the 2nd 60 miles, the total distance will be 120mi in one hour plus however long it takes to do the second half, so the average speed will always be under 120mph.[/hide]

 

Good riddle, made me think about things ect.

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[hide=]well lets see

 

 

 

lets say the distance is 120miles

 

 

 

the first half will take an hour

 

 

 

going 180mph it will take 20 minutes to finish the 120miles

 

 

 

120 miles divided by 80 minutes=3/2 miles per min=90mph

 

 

 

going 240mph it will take 15 minutes to finish the 120 miles

 

 

 

120 miles divided by 75 minutes=24/15 miles per min=144/15mph=96mph

 

 

 

going 600mph it will take 10 minutes to finish the 120

 

 

 

120 miles divided by 70 minutes=12/7 miles per minute=720/7=102.8(approx)

 

 

 

going 1200 mph it will take 5 minutes to finish the 120

 

 

 

120/65=110.7mph[/hide]

 

 

 

after playing with that I see the solution fastortoise came up with

 

 

 

[hide=]since your time for an arbitrary 120 miles is at greater then 60 and 120/60=2miles per minute=120 miles per hour. For a speed less then infinity the time will be 120/(60+x) where x is a positive number leaving us with an mph of less then 120[/hide]

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Orthodoxy is unconciousness

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This seems to be the most famous riddle in statistics, used in books like The Curious Incident of the Dog in the Nighttime and in the movie 21:

 

 

 

You're playing a game show and are shown 3 doors. Behind one door is a new car, behind the other two are goats. You are told to pick one door. After you pick the door, before it is revealed, the host (who knows whats behind each door) chooses another door that has a goat behind it. You now have 2 doors left, and the host asks if you want to switch picks before the door is opened. Is it to your benefit to switch your choice of door in order to win the car?

 

 

 

The answer to the riddle is yes, it increases your chances of winning the car. But I'm not entirely sure how they arrived at that conclusion. I haven't taken a class in statistics yet so I haven't the faintest clue, it doesn't make sense to me at all. Anyone care to elaborate?

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tip it would pay me $500.00 to keep my clothes ON :( :lol:
But then again, you fail to realize that 101% of the people in this universe hate you. Yes, humankind's hatred against you goes beyond mathematical possibilities.
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Apparently a lot of people say it. I own.

 

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Search Monty Hall problem on youtube.

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So, what is 1.111... equal to?

10/9.

 

Please don't continue.

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The answer to the riddle is yes, it increases your chances of winning the car. But I'm not entirely sure how they arrived at that conclusion. I haven't taken a class in statistics yet so I haven't the faintest clue, it doesn't make sense to me at all. Anyone care to elaborate?

 

 

 

If you haven't already figured it out...

 

 

 

Because there are three doors to choose from and you're choosing randomly you have about a 33% chance of choosing correctly. Then the host removes a door as an option. If you are indeed wrong about your first choice, then the prize could have originally been in either of the two doors you didn't choose. The host would know which door didn't have the prize and removes that door for you. He is helping you by effectively combining the total probability of the two doors into one door because he would have gotten rid of the wrong door no matter which door the prize was behind.

 

 

 

This was horrendously explained and you're better off searching for the explanation on the internet somewhere :-( But I thought I would post it anyway.

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This seems to be the most famous riddle in statistics, used in books like The Curious Incident of the Dog in the Nighttime and in the movie 21:

 

 

 

You're playing a game show and are shown 3 doors. Behind one door is a new car, behind the other two are goats. You are told to pick one door. After you pick the door, before it is revealed, the host (who knows whats behind each door) chooses another door that has a goat behind it. You now have 2 doors left, and the host asks if you want to switch picks before the door is opened. Is it to your benefit to switch your choice of door in order to win the car?

 

 

 

The answer to the riddle is yes, it increases your chances of winning the car. But I'm not entirely sure how they arrived at that conclusion. I haven't taken a class in statistics yet so I haven't the faintest clue, it doesn't make sense to me at all. Anyone care to elaborate?

 

 

 

http://www.youtube.com/watch?v=C5NPpoM5 ... re=related

 

 

 

The entire video, and all of QualiaSoup's videos are great.

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You have a 9 dot box. How can you fill it up without taking the pencil off the paper and can only write 4 lines?

Don't you know the first rule of MMO's? Anyone higher level than you has no life, and anyone lower than you is a noob.

People in OT eat glass when they are bored.

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The answer to the riddle is yes, it increases your chances of winning the car. But I'm not entirely sure how they arrived at that conclusion. I haven't taken a class in statistics yet so I haven't the faintest clue, it doesn't make sense to me at all. Anyone care to elaborate?

 

 

 

If you haven't already figured it out...

 

 

 

Because there are three doors to choose from and you're choosing randomly you have about a 33% chance of choosing correctly. Then the host removes a door as an option. If you are indeed wrong about your first choice, then the prize could have originally been in either of the two doors you didn't choose. The host would know which door didn't have the prize and removes that door for you. He is helping you by effectively combining the total probability of the two doors into one door because he would have gotten rid of the wrong door no matter which door the prize was behind.

 

 

 

This was horrendously explained and you're better off searching for the explanation on the internet somewhere :-( But I thought I would post it anyway.

 

That's so cool! If I ever get on a game who, I'll use that :lol:

 

 

 

I've never been one for math in any form...

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"It's not a rest for me, it's a rest for the weights." - Dom Mazzetti

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Found this to be funny.

 

 

 

Salary Theorem: The less you know, the more you make.

 

Proof:

 

Fact #1: Knowledge is Power

 

Fact #2: Time is Money

 

We know that: Power = Work / Time

 

And since Knowledge = Power and Time = Money

 

It is therefore true that Knowledge = Work / Money

 

Solving for Money, we get:

 

Money = Work / Knowledge

 

Thus, as Knowledge approaches zero, Money approaches infinity, regardless of the amount of Work done

 

And this is why we have liberal arts/english majors working at Starbucks.

 

 

 

Or because their degrees are worthless. Whatever helps you sleep at night.

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These aren't really riddles, but questions I've been wondering.

 

 

 

1. Are there an infinite or finite amount of colors?

 

2. There are an infinite amount of positive numbers. There are also an infinite amount of negative numbers. So, there are an infinite amount of numbers plus another set of infinite numbers when you take the negatives into account. (infinity + infinity) Does this mean something can be over infinity?

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2. There are an infinite amount of positive numbers. There are also an infinite amount of negative numbers. So, there are an infinite amount of numbers plus another set of infinite numbers when you take the negatives into account. (infinity + infinity) Does this mean something can be over infinity?

 

 

 

Infinity + -Infinity = Infinity - Infinity = 0

 

 

 

I'm obviously wrong, but it doesn't hurt to try.

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These aren't really riddles, but questions I've been wondering.

 

 

 

1. Are there an infinite or finite amount of colors?

 

2. There are an infinite amount of positive numbers. There are also an infinite amount of negative numbers. So, there are an infinite amount of numbers plus another set of infinite numbers when you take the negatives into account. (infinity + infinity) Does this mean something can be over infinity?

 

 

 

1.infinite colors; since its subjective what divides two colors we can continually break the spectrum into halves then fourths and so on ad infinitum

 

 

 

2. There are different degrees of infinity; the set of all positive (whole) numbers is small then the set of all positive and negative(whole) number, but both are infinite sets.

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Orthodoxy is unconciousness

the only ones who should kill are those who are prepared to be killed.

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These aren't really riddles, but questions I've been wondering.

 

 

 

1. Are there an infinite or finite amount of colors?

 

 

I had a yarn with a mate about this. He was wondering if somewhere out in space there is a colour that we have never seen before and we wouldn't know what it would look like because we have never seen it before,

 

I said that it would still be familair to us and yadda yadda yadda

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I had a yarn with a mate about this. He was wondering if somewhere out in space there is a colour that we have never seen before and we wouldn't know what it would look like because we have never seen it before,

 

I said that it would still be familair to us and yadda yadda yadda

 

 

 

Colours are merely reflected light, which is the visible part of the electromagnetic spectrum:

 

http://www.yorku.ca/eye/spectrum.gif

 

 

 

So if we develop a way for our eyes to see x-rays/microwave rays ect... then those would have a "colour".

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