Even knowing that this is a trick question....even having seen it before.....I still got it wrong.
Here’s a simple arithmetic question:
A bat and ball cost a dollar and ten cents. The bat costs a dollar more than the ball. How much does the ball cost?
4 comments:
I'm afraid to answer although the answer seems obvious to me. I can't answer because I might be wrong and if I'm wrong I'd be a failure. I'm afraid to fail.
To me, the answer is obvious, too. Even doing the math quickly, its obvious. Its just wrong.
Everyone thinks Oh, thats obvious - a dollar for the bat, ten cents for the ball. But its not. This is how you solve it.
Given - Cost of Bat + Cost of Ball = $1.10
The Cost of the Bat is $1 more than the Cost of the Ball, so
Cost of Bat = Cost of Ball + $1
or to show it a little differently)
Cost of Bat = (Cost of Ball + $1)
Since the Cost of Bat = (Cost of Ball + $1) (because we know that the bat costs a dollar more than the ball), you can substitute in the first equation, and change
Cost of Bat + Cost of Ball = $1.10
to
(Cost of Ball + $1) + Cost of Ball = $1.10.
Subtract one dollar from each side -
(Cost of Ball) + Cost of Ball = 0.10
Since you have two 'Cost of Balls' being equal to ten cents, that is the same as saying
2*Cost of Ball = 0.10.
If two 'Cost of Ball's is ten cents, then one Cost of Ball is five cents. And if the Ball is five cents, and the Bat + Ball is $1.10, then the Bat must be $1.05 -- which is one dollar more than the ball.
I had it at a nickel!
How I figured it out was: bat = $1
Difference = $1
Therefore, the ball can't cost 10c, because then the cost would be $1.20; the ball has to cost less than that. So... divide and conquer - if the bat cost $1.05 (half way between $1 and $1.10) then... Good grief I figured it out! :-)
You did much better than I, CA.
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