To find the percentage of 6th graders who did between 6 and 14 push-ups, we need to calculate the interquartile range first. The interquartile range is the difference between the upper quartile and the lower quartile, which is 14 - 6 = 8.
Then, we calculate the total range of push-ups, which is the difference between the maximum value and the minimum value, which is 21 - 0 = 21.
The percentage of 6th graders who did between 6 and 14 push-ups is then given by the interquartile range divided by the total range and multiplied by 100:
(8/21) * 100 = 38.1%
Therefore, approximately 38.1% of 6th graders did between 6 and 14 push-ups.