A what-if analysis that you could perform using spreadsheet software would be useful for 

answering the question 

a. How will it affect the total I pay for my car if I pay an extra $100 per month on my car loan? 

b. What if I change the color of my Web page banner from blue to bright red? 

c. How can I get an A on my next two economics exams? 

d. Will my favorite company's stock outperform the stock of their competitor over the next two years