Marian is a Product Owner working on a Scrum Team on a new release for her product. Based on the average velocity of the previous release Marian estimated the project to take seven Sprints. Average velocity in the previous release was thirteen completed units of work per Sprint. Development is three Sprints underway, with four more Sprints to go until the release. Product Backlog has been stable.
Over the first three Sprints, the Developers report their average velocity is nine, while not having fully tested all the delivered functionality. The Developers estimate that the unfinished testing would have required 10% of a Sprint's time. The Developers believe that the required velocity of thirteen is within their reach. What is the most effective way to recover?