A regional office of the Internal Revenue Service randomly distributes returns to be audited to the pool of auditors. Over the thousands of returns audited last year, the average amount of extra taxes collected was $356 per audited return. One of the auditors, Jeffrey Jones, is suspected of being too lenient with persons whose returns are being audited.

For a simple random sample of 30 of the returns audited by Mr. Jones last year, an average of $322 in extra taxes was collected, with a standard deviation of $90.

Based on this information and a hypothesis test of your choice, do the suspicions regarding Mr. Jones appear to be justified?