A mathematician, an accountant and an economist apply for the same job.

The interviewer calls in the mathematician and asks What do two plus two equal?

The mathematician replies Four.

The interviewer asks Four, exactly? The mathematician looks at the interviewer incredulously and says

Yes, four, exactly.

Then the interviewer calls in the accountant and asks the same question What do two plus two equal? The

accountant says On average, four – give or take ten percent, but on average, four.

Then the interviewer calls in the economist and poses the same question What do two plus two equal?

The economist gets up, locks the door, closes the shade, sits down next to the interviewer and says What do you want it to equal?