Written Job Application

Two young men with equal qualifications apply for the same job. In order to determine which individual to hire, the manager gives them a written test. Both men score nine out of 10 on the test; however, the manager decides to go with the first applicant.
"Why would you do that?" asks the rejected second applicant. "We both got nine questions correct."
"Your fellow applicant wrote 'I don't know' for question five. You put down, 'Neither do I.'"