Porisma

Worked solution

Compare the two opening dice events

Which is more likely: getting at least one six in 4 rolls of one die, or getting at least one double six in 24 rolls of two dice?

CJC · Lecture · Exploration Activity

Count the complement of no six in four rolls

Assume fair dice and independent rolls. A single roll misses six with probability 5/6, so the chance of at least one six in four rolls is 1−(5/6)4≈0.5177471-(5/6)^4\approx0.517747.

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Count the complement of no double six in twenty-four rolls

A pair of independent fair dice shows double six with probability 1/36. Thus the chance of at least one double six in 24 rolls is 1−(35/36)24≈0.4914041-(35/36)^{24}\approx0.491404.

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Compare the probabilities

The first event is more likely: about 51.8%versus 49.1%. The opening source poses the question without a worked answer; these calculations are supplementary. Multiplying the number of rolls by the one-roll success probability is not the probability of at least one success.

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Common mistakes

State the fair-dice and independent-roll assumptions. Count at least one success using the complement of no successes, not by adding overlapping success events.

Read the hint