For example, if you spent $1.10 on a baseball glove and a ball, and the glove cost $1 more than the ball, how much did the ball cost?
Hint: The answer isn't 10 cents!
I came across this in an article about making predictions: http://www.nytimes.com/2013/03/22/opini ... share&_r=0.
This is the kind of question used to assess people's open-mindedness.
You can cheat and find the answer in the article. I initially doubted it, but if you apply algebra to the problem you'll find out that their answer is correct.
Jeff
Riddle
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JollyGreen
- Posts: 2047
- Joined: Sat Mar 21, 2009 10:06 am
The mistake most people make is they forget one item was $1.00 MORE than the other item. This means you cannot subtract the cost of the glove from the total to calculate the price of the ball.
I'm not sure I post the answer Jeff? Will that spoil it?
I'm not sure I post the answer Jeff? Will that spoil it?
I think it will be OK if we use a spoiler alert.
SPOILER ALERT - ANSWER AT THE END OF THIS MESSAGE!!!
5 cents
Here's the proof. Let g = the glove and b equal the bat:
g+b=1.1
g+1=b
Therefore:
g+b+g+1=1.1+b
Rearranging this gives:
2g = 0.1
so g = 0.05
JollyGreen wrote: I'm not sure I post the answer Jeff? Will that spoil it?
SPOILER ALERT - ANSWER AT THE END OF THIS MESSAGE!!!
5 cents
Here's the proof. Let g = the glove and b equal the bat:
g+b=1.1
g+1=b
Therefore:
g+b+g+1=1.1+b
Rearranging this gives:
2g = 0.1
so g = 0.05
-
JollyGreen
- Posts: 2047
- Joined: Sat Mar 21, 2009 10:06 am
There is a formula that is easier to read and understand
Scroll down if you want to read it...
The glove costs $1.00 and the total spend is $1.10. The unknown is x but we know the glove costs x + $1
Therefore
x + ($1.00 + x) = $1.10
$1.00 + 2x = $1.10
2x = $1.10-$1.00
2x = $0.10
x = $0.10 / 2
x = $0.05
So the ball costs 5 cents
Scroll down if you want to read it...
The glove costs $1.00 and the total spend is $1.10. The unknown is x but we know the glove costs x + $1
Therefore
x + ($1.00 + x) = $1.10
$1.00 + 2x = $1.10
2x = $1.10-$1.00
2x = $0.10
x = $0.10 / 2
x = $0.05
So the ball costs 5 cents
Just noticed this interesting comment made by a reader of the forecasting article:
'The problem with predictive models is that the existence of these models quickly become part of the system you are modeling. For example, if someone created a model that predicted the movement of stocks, then very quickly people would change their behaviour by using this model to decide what stocks to buy or sell, thereby rendering the model obsolete.'
Jeff
'The problem with predictive models is that the existence of these models quickly become part of the system you are modeling. For example, if someone created a model that predicted the movement of stocks, then very quickly people would change their behaviour by using this model to decide what stocks to buy or sell, thereby rendering the model obsolete.'
Jeff
question: what is better than happiness?Ferru123 wrote:I think it will be OK if we use a spoiler alert.SPOILER ALERT - ANSWER AT THE END OF THIS MESSAGE!!!JollyGreen wrote: I'm not sure I post the answer Jeff? Will that spoil it?
5 cents
Here's the proof. Let g = the glove and b equal the bat:
g+b=1.1
g+1=b
Therefore:
g+b+g+1=1.1+b
Rearranging this gives:
2g = 0.1
so g = 0.05
Answer: Nothing
question: what would you choose between a hamburger and nothing?
Answer: a hamburger
Now I just demonstrated you that a hamburger is better than happiness
in the end g=glove costs 5centsFerru123 wrote:I think it will be OK if we use a spoiler
5 cents
Here's the proof. Let g = the glove and b equal the bat:
g+b=1.1
g+1=b
Therefore:
g+b+g+1=1.1+b
Rearranging this gives:
2g = 0.1
so g = 0.05
and bat 1.05
how much did the ball cost then?
