15°C 21°C 27°C 33°C
I gave my students this multiple choice question: The average temperatures over a four-month period were 31, 24, 18, and 12 degrees Celsius. What is the median temperature for these four months?

Only one answer is correct among these 4 choices:
- 15°C
- 21°C
- 27°C
- 33°C

Could you tell me which one is correct?

21°C