What is it called when the effect of one independent variable depends on the level of another independent variable?

Chester has a credit score of 595 according to the following table his credit rating is considered to be which of these

Email viruses are typically launched by people who modify header information to hide their identity. brightmail's enrique salem says that in the future, your email reader will authenticate the sender before putting hte message in your inbox. that way, you will know the source of all the emails you read. alan nugent of novell says, "i'm kind of a fan of eliminating anonymity if that is the price for security." will eliminating anonymity make computers more secure?

Lusk corporation produces and sells 14,300 units of product x each month. the selling price of product x is $25 per unit, and variable expenses are $19 per unit. a study has been made concerning whether product x should be discontinued. the study shows that $72,000 of the $102,000 in monthly fixed expenses charged to product x would not be avoidable even if the product was discontinued. if product x is discontinued, the annual financial advantage (disadvantage) for the company of eliminating this product should be: