In this scenario, the factor that will not impact Dexter's chances of getting the job is:
Applicants must have five years’ experience in an office environment. Dexter worked as a part-time admin assistant while studying for his diploma.
This is because Dexter does have some relevant experience, even if it is part-time, which may be considered by the employer. The other factors mentioned—lack of understanding of filing and data capturing, communication skills impacted by a speech impediment, and insufficient experience with Excel—are likely to have a more direct impact on his chances of getting the job.