Stats Problem Help

I am reviewing some old stats work to freshen up for a new job..They gave me some review stuff and this was one of the questions I am somewhat stuck on. How would you guys go about doing this? What test would you use? I use PHSTAT software and Excel. Or by hand, anything would help.

The IRS claims that they have less that 1% errors on electronically filed returns. A random sample of 400 returns shows 3 errors. Analyze this situation and give your conclusions.

Thanks a lot