"21. According to Apple's iTunes App Store, 630,210 active applications (apps) were available for download as of May 1, 2012. Below is a table showing monthly sub-missions of new applications to the App Store from March 2011 through April 2012 (source: 148apps.biz).

Determine the interquartile range for the submissions data.

Month SubmittedApps

2011-03 19,853

2011-04 20,025

2011-05 18,259

2011-06 20,249

2011-07 18,031

2011-08 20,687

2011-09 20,177

2011-10 20,221

2011-11 19,229

2011-12 21,691

2012-01 21,082

2012-02 19,622

2012-03 23,245

2012-04 22,795"