Multiple choice

A box contains $12$ different black balls, $7$ different red balls and $6$ different blue balls. In how many ways can the balls be selected?

  1. $2^{25}-1$
  2. $2^{25}$
  3. $728$
  4. $727$
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A Correct answer
Explanation

For each of the 25 distinct balls, one can either select it or not select it. This gives 2^25 combinations. We subtract 1 to exclude the case where no balls are selected.

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