We are given that Bank A charges ordinary interest for a loan of $11000 at a rate of 9% for a period of 90 days, we can calculate the total interest using the formula for ordinary interest, this is:
Replacing that we get:
Solving we get:
Now, bank B charges exact interest, the formula is:
Replacing we get:
solving the operation:
Therefore, she will pay less interest to Bank B. Bank B offers a better deal.