A standard fair six-sided die is rolled once. What is the probability of rolling a 4? Give the probability as a fraction out of the six equally likely faces.

الشرح

Exactly one face carries a 4 and all six faces are equally likely, so one favourable face is counted against six possibilities, giving 1/6. Answering 4/6 puts the number printed on the face into the count of favourable outcomes, but that 4 names the face rather than saying how many faces qualify, and only one does.