The ScrumMaster is a full Team Member of the Scrum Team and is required to be focused on helping the team achieve its goals. However, he does not do the work of the Sprint Backlog. Instead he focuses his energies on removing obstacles and helping use Scrum as best as possible. One way to achieve these goals is to be able to respond to questions by the team within minutes. If the ScrumMaster is able to do, the team will move faster, solve problems easier, and cut through obstacles much sooner. If the ScrumMaster is not able to do this, the team will become stalled, frustrated and likely lose trust in the ScrumMaster and the Scrum process.
To learn more about your ScrumMaster, visit the Scrum Team Assessment.