A multiple of 3 is either 3 or 6. Out of the 6 possible outcomes of rolling a number cube, 2 of them are multiples of 3. Therefore, the probability of rolling a multiple of 3 on one cube is $\frac{2}{6}=\frac{1}{3}$. Since the two cubes are identical, this probability is the same for rolling a multiple of 3 on the other cube.
To find the probability of both events happening, we multiply the probabilities:
$\frac{1}{3} \cdot \frac{1}{3} = \frac{1}{9}$
So the answer is $\boxed{\textbf{(D) }one-ninth}.$
Eric has two identical number cubes. The faces of each cube are numbered 1–6. Eric will roll both of the number cubes at the same time. What is the probability that both of the numbers showing face-up will be multiples of 3?
A. two-ninths.
B. one-third.
C. start fraction 1 over 6 end fraction.
D. one-ninth.
1 answer