1. Randomly throw three identical cubic dice. The probability that the minimum value among the three dice is 3 is $\qquad$ .
$-1 . \frac{37}{216}$.

The probability that all dice show a number of at least 3 is $\left(\frac{4}{6}\right)^{3}$, and the probability that all dice show a number of at least 4 is $\left(\frac{3}{6}\right)^{3}$. Therefore, the probability that the smallest number shown by the three dice is exactly 3 is $\left(\frac{4}{6}\right)^{3}-\left(\frac{3}{6}\right)^{3}=\frac{37}{216}$.