11. (10 points) Please divide the numbers $12, 15, 33, 44, 51, 85$ into two groups, so that the product of the four numbers in each group is equal.
【Analysis】Divide the 6 numbers in the question into odd and even groups and perform prime factorization, according to the number of prime factors in both groups being equal, the solution can be derived.

【Solution】Solution: Odd group: $15=3 \times 5$
$$
\begin{array}{l}
33=3 \times 11 \\
51=3 \times 17 \\
85=5 \times 17
\end{array}
$$

Even group: $12=2 \times 2 \times 3$
$$
44=2 \times 2 \times 11
$$

First, divide the two even numbers into two groups:
The first group contains $12,33$, and the prime factors of $12$ include 3, so 51 is placed in the other group; 85, which contains the prime factor 5, is placed in the other group with 15;

The second group contains 44, which has the factor 11, so the other number containing the factor 11, 33, is placed in the first group; 51, which contains two prime factors 17, so the two numbers containing the prime factor 17, 85, are placed in the first group; 15;
$$
\text { That is: } 12 \times 33 \times 85=44 \times 51 \times 15 \text {. }
$$

Answer: The first group has $12,33,85$; the second group has $44,51,15$.