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Problem 31

Combinatorics Difficulty 1.1 Multiple choice CEMC Gauss (Grade 8) · Canada · 2012

A six-sided die has the numbers one to six on its sides. What is the probability of rolling a five?

Pick one

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Official solutions — 2

Solution 1

Each of the numbers 1,2,3,4,5,1,2,3,4,5, and 6 is equally likely to appear when the die is rolled.

Since there are six numbers, then each has a one in six chance of being rolled.
The probability of rolling a 5 is 16\frac{1}{6}.

Solution 2

Written numerically, the number 33 million is 33 000 000.

Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty, ordering) added by this project.