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Comment by vain | Hacker News Reader

A bat and ball cost a dollar and ten cents. The bat costs a dollar more than the ball

  bat + ball = 1.1
  bat = ball + 1
  2bat + ball = ball +1.1 +1
  2bat = 2.1
  bat = 1.05
  ball =0.05

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My thought process went, "a dollar is 90 cents more than 10 cents, so $1.05 is a dollar more than five cents".

I made exactly the same fallacy as those in this study; I've just learned to check my work. On the other hand, I suspect the whole process of estimation and refinement was faster than writing out those equations.

bat - ball = 1

1 - .1 = .9

1.05 - .05 = 1

I parsed that as:

    bat = 1.1
    ball = 1.1  
    bat = ball + 1

It confused the hell out of me.

I immediately switched to generic variables X and Y, rather than keeping the original names. It helps.

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