This question is based on the scores from a sample of 12 people - all of whom completed a 5-item scale that you created ("attitudes towards eating leafy green vegetables). Response options were based on a 5-point Likert scale, with "5" being highly favorable. The summed scores ranged from 5 to 25, and appear below (in ascending order).

24 22 21 20 20 20 17 15 15 7 6 6

What is the variance of this distribution?