After three completed sprints you look at a release burn down “bar” chart. The diagram initially starts with 400 story points on its Y-axis. The following happened in the three sprints:
Sprint 1 45 story points planned 40 story points completed
Added 20 story points to the backlog Sprint 2 45 story points planned 40 story points completed
Removed 30 story points from the backlog Sprint 3
40 story points planned Completed 30 story points 10 story points almost complete Removed 10 story points from the backlog