An auditor collected a random sample of about 100 invoices sent out in the current fiscal year and compared the amounts of these invoices to those of a second random sample of invoices in the prior...

An auditor collected a random sample of about 100 invoices sent out in the current fiscal year and compared the amounts of these invoices to those of a second random sample of invoices in the prior fiscal year. These boxplots summarize the amounts (in dollars) of the two sets of invoices.

Would you suggest that the auditor perform a twosample
-test to compare the mean values of these invoices, or can you suggest one (or more) lurking factors that should be taken into account prior to the comparison?