Final answer:
The effective annual rate for XYZ Corporation if they decide to pay the bill in 30 days is approximately 44.58%.
Step-by-step explanation:
The effective annual rate for XYZ Corporation if they decide to pay the bill in 30 days can be calculated using the formula:
Effective Annual Rate = (1 + (2 / 98))(365/20) - 1
Substituting the values, the effective annual rate would be approximately 44.58%.
This means that if XYZ Corporation delays payment for 30 days, the annual interest they would effectively be paying on the $100 bill from Mahan Corporation is approximately 44.58%.