18 mice were placed in two experimental groups and one control groups with all groups equally large. In how many ways can the mice be placed into three groups ?

Explanation

To solve the problem of how many ways 18 mice can be placed into three equally large groups, we can follow these steps:

### Step 1: Understand the Problem
We have 18 mice and we need to divide them into three groups (two experimental groups and one control group) such that each group has an equal number of mice.

### Step 2: Determine the Size of Each Group
Since there are 18 mice and 3 groups, the number of mice in each group will be:
\[
...