Where did you get this problem? Are you not taking a course in, perhaps, "probability and statistics"? If so you should at least know what is meant by a "97% cofidence interval"? And you certainly should know that you have to havesomeinformation to construct one. Where did that "$110" come from? Where did that "$420" come from? If some agency says that the mean is $110 (and thinks that is too high) what information could you have that you should say it is actually almost four times that value? Are you sure you have copied the problem correctly?