Classroom Division Puzzle: Calculating Total Students from Even Groups

A teacher divides the students in her class into even discussion groups,

How many students are in the class?

Let's solve this problem step by step.

• Step 1: As defined by the problem, the total number of students in the class needs to be an even number.
• Step 2: According to simple divisibility rules, an even number ends in 0, 2, 4, 6, or 8. We apply this rule to the answer choices.
• Step 3: The answer choices are:
  • 41, which is odd.
  • 31, which is odd.
  • 21, which is odd.
  • 22, which ends in 2 and is even.
• Conclusion: The only even number among the choices is 22.

Therefore, the correct answer is $22$.