Three dice are rolled. Find the number of possible outcomes in which at least one die shows 5.

Required number of possible outcomes $=($ Total number of outcomes $-$ Number of possible outcomes in which 5 does not appear on any of the dice.)

Total number of outcomes when a single dice is rolled $=6$

$\therefore$ Total number of outcomes when two dice are rolled $=6 \times 6$

Similarly, total number of outcomes when three dice are rolled $=6 \times 6 \times 6=216$

Number of possible outcomes in which 5 does not appear on any dice $=5 \times 5 \times 5=125$

$\therefore$ Required number of possible outcomes $=216-125=91$