Job interview!

While being interviewed for a job, the personnel manager said to the Maguire brothers:

'We're going to give you a written examination. Ten questions. Whoever gets most right we'll hire.'

Papers were produced and the boys set to work answering the general knowledge questions. When the time was up the personnel manager collected and marked the papers.

'Well,' said he, 'you've both got nine out of ten, but I'm giving Mick the job.'

'Why's that?' asked Pat.

'Well,' said the manager, 'you both got the same question wrong but he had

'I don't know this' and you had 'Neither do I!'.