In the Cola Example, suppose that each customer makes one purchase of cola during any week.
Suppose there are 100 million cola customers.
One selling unit of cola costs the company $1 to produce and is sold for $2.
For $500 million/year, an advertising firm guarantees to decrease from 10% to 5% the fraction of cola 1 customers who switch after a purchase.
Should the company that makes cola 1 hire the firm?