Math Puzzles!

[Jason Tandro]

Okay, I don't know why my brain is the way it is, but I abhor math in practice. Like seriously detest it, hated taking it is school, Algebra can kiss my ass (though for some reason, I really enjoyed Trigonometry).

But... I can take a good deal of the skills I learned and apply them to math puzzles, which I find really awesome. Though ocassionally I screw up.

Exhibit A:

A game costs $1 plus half it's cost. How much does it cost?

Well, on the place where I heard this a good number of people were saying either $1.50 or that it was a paradox. If the answer really was $1.50 it would be a pretty lame puzzle. So I reasoned it was a paradox, and here's how I reasoned.

Where game price = x, our statement reads thus:

X = 1 + (x/2)
2x = 1 + x
2(1) = 1+1
2 = 2
therefore x =1.

And this contradicts the earlier statement of x = 1 + (x/2).

Now, before scrolling down, can anybody see where I screwed up?















Okay, so when I applied the transitive property by multiplying both sides of the equation to 2, I forgot to also multiply my constant.

Therefore it should have read.

2x = 2 + x

And therefore we can tell that

2(2) = 2+2

or

x = 2



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So, anybody know of any other good math puzzles?

[inferiare]

Get out. I won't allow math on my boards.



...I kid. But seriously, WHY MATH ARE YOU TRYING TO BURN ME LIKE PEOPLE BURNED WITCHES?

[EverPhoenix]

Or, do it the easy way:

x = 1 + x/2;
0.5x = 1;
x = 2;

Game costs $2.

I've seen other fun puzzles which are along the lines of:

George is twice as old as Sam was when George was Sam's age. When Sam reaches George's age, the sum of their ages will be triple what Sam's is now.

There might be some info missing. Have fun with simultaneous equations.