Final answer:
To find the probability of getting at least one multiple of 3 when rolling a six-sided number cube 5 times, we subtract the probability of not getting any multiples of 3 from 1.
Step-by-step explanation:
To find the probability of getting at least one multiple of 3 when rolling a six-sided number cube 5 times, we need to find the probability of getting no multiples of 3 and subtract it from 1.
The probability of not getting a multiple of 3 on a single roll is 4/6, because there are 4 numbers out of 6 that are not multiples of 3. Since the rolls are independent, the probability of not getting a multiple of 3 on all 5 rolls is (4/6)^5.
Therefore, the probability of getting at least one multiple of 3 is 1 - (4/6)^5.