A pupil answers 1/6 for the probability of not rolling a 6 on a standard fair six-sided die. What is the probability of not rolling a 6, as a fraction out of the six equally likely faces?

Explication

Five of the six faces show something other than a 6, so the event succeeds on five faces out of six. The pupil's figure of 1/6 is the probability of rolling the 6 itself, which is precisely the result the question asks to avoid, and the two figures together account for all six faces.