One, Two, Three Dice

May 13, 2015 in Mathematics

Which one would you bet on? Throw 6 dice and get at least one 6, 12 dice and get at least two 6’s, or 18 dice and get at least three 6’s?

Let’s do the math. The probability of throwing 6 dice and getting at least one 6 is:

\[1 - \binom{6}{0}\times\frac{5^6}{6^6} ≈ \underline{0.665}\]

The probability of throwing 12 dice and getting at least two 6’s is:

\[1 - \left(\binom{12}{0}\times\frac{5^{12}}{6^{12}} + \binom{12}{1}\times\frac{5^{11}}{6^{12}}\right) ≈ 0.619\]

The probability of throwing 18 dice and getting at least three 6’s is:

\[1 - \left(\binom{18}{0}\times\frac{5^{18}}{6^{18}} + \binom{18}{1}\times\frac{5^{17}}{6^{18}} + \binom{18}{2}\times\frac{5^{16}}{6^{18}}\right) ≈ 0.597\]

Shocked?

who am i

I am a Principal Research Engineer at Arm, ex-Professor of Software Engineering at the Faculty of Engineering, University of Porto and Research Associate at INESC TEC. Here you can find my PhD Thesis, my Résumé (not updated since 2020), and my Publications.

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This is a blog about software, some mathematics, and the occasional philosophy. Not necessarily in that order.

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