An idler sighed: “Everyone says, ‘We don’t need idlers. You are always in the way. Go to the devil!’ But will the devil tell me to get rich?”
No sooner did the idler say this than the devil himself stood in front of him.
“Well,” said the devil, “the work I have for you is light, and you will get rich. Do you see that bridge? Just walk across and I will double the money you have now. In fact, each time you cross I will double your money.”
“You don’t say!”
“But there is one small thing. Since I am so generous you must give me $24 after each crossing.”
The idler agreed. He crossed the bridge, stopped to count his money …a miracle! It had doubled.
He threw $24 to the devil and crossed again. His money doubled, he paid another $24, crossed a third time. Again his money doubled. But now he had only $24, and he had to give it all to the devil. The devil laughed and vanished.
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The moral: When anyone gives you advice you should think before you act. How much money did the idler start with?
Answer:
It is probably best to think about this backwards. Before the third crossing the idler had $12. Adding the $24 he gave the devil after the second crossing, he had $36, twice the $18 he had before the second crossing. Adding $24 again, he had $42, twice the $21 he started with.
My dad told me this one.
When I was as old as you are, you were half as old as I am. When you are as old as I am, together we'll be 63. How old am I?
Hey, Tensor. I got it; thanks for the diversion!
But in what way is this not a math puzzle? (Variations on it, with different things that happen during the iteration, are standard fare in math classrooms and math teacher training workshops.)
Lets call this a .
I'm trying to alleviate math-phobia with the power of suggestion.
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I got it right, but all I can say is... You know who isn't a genius? The guy who crossed the bridge...
Hey, Tensor. I got it; thanks for the diversion!
But in what way is this not a math puzzle? (Variations on it, with different things that happen during the iteration, are standard fare in math classrooms and math teacher training workshops.)
Lets call this a .
** spoiler omitted **
Waitaminute...there was math involved in that problem! FRAUD! FRAUD!
Yes, it is.
But I got it.
Still trying to parse the sentence on the age thing.
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My dad told me this one.
When I was as old as you are, you were half as old as I am. When you are as old as I am, together we'll be 63. How old am I?
** spoiler omitted **
Finally got it.
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My dad told me this one.
When I was as old as you are, you were half as old as I am. When you are as old as I am, together we'll be 63. How old am I?
** spoiler omitted **
Finally got it.
** spoiler omitted **
** spoiler omitted **
x+(x-y)+y+(x-y)=63 => 3x-y = 63 => 3y=63
RPG Superstar 2010 Top 16
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I got the same answer as Calixymenthillian, but I chose to set the variables as Y = "your current age" and D = difference in ages.
So the speaker's current age is Y + D.
The restrictions literally translate then as:
Y - D = 1/2 (Y + D)
and
(Y + D) + (Y + D + D) = 63.
The first sentence simplifies down to
Y = 3 * D.
So we substitute "3D" into the second equation wherever there's a Y.
(3D + D) + (3D + D + D) = 63
9D = 63.
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** spoiler omitted **My dad told me this one.
When I was as old as you are, you were half as old as I am. When you are as old as I am, together we'll be 63. How old am I?
** spoiler omitted **
Finally got it.
** spoiler omitted **
** spoiler omitted **
Those don't fit the first constraint (as I read it):
Math hurt brian...have urge to weggie nurd...Aarrggg...
Finally got it.
You might want to check your math. :-)
My answer
Calixy has it. :-)
Hulk am hate Math!! Hulk smash puny Math!!!!
I got the same answer as Calixymenthillian, but I chose to set the variables as Y = "your current age" and D = difference in ages.
My dad once figured out how to solve it with one variable. I can't remember how he did it, though. It was back when I was still just trying to figure out what the riddle was asking.
Uh, can I just say that that one about the ages works so much better in real-world terms if it's about the age of a pair of siblings than about a father and child.
It's not about a father and child. I mentioned that my dad told me the riddle. However, he wasn't talking about us. After all, when he was as old as I am, I wasn't born yet. :P
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RPG Superstar 2010 Top 16
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My dad once figured out how to solve it with one variable. I can't remember how he did it, though. It was back when I was still just trying to figure out what the riddle was asking.
Well, it's a system of two equations in two unknowns. You can solve them simultaneously or, as we've been discussing, by substitution. But there's no way to start the process with only one unknown.
Well, it's a system of two equations in two unknowns. You can solve them simultaneously or, as we've been discussing, by substitution. But there's no way to start the process with only one unknown.
I wholeheartedly agree with you. However, I'm just telling you what I remember.
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Well, it's a system of two equations in two unknowns. You can solve them simultaneously or, as we've been discussing, by substitution. But there's no way to start the process with only one unknown.I wholeheartedly agree with you. However, I'm just telling you what I remember.
He may have been using substitution but glossing over that part, so the first step that he put down on paper was where he had already reduced it to one variable.