Some observers were left wondering why Apple would continue to sell the iPad 2 for $399 after announcing the iPad Air and Retina iPad mini. The answer: based on new research from Consumer Intelligence Research Partners, customers are still buying the two-year old tablet. In fact, the iPad 2 accounted for roughly 22% of iPad sales in the September quarter, down significantly from prior quarters. It appears there is still more than enough demand for a cheaper, full-size iPad, particularly for the education sector.