Final answer:
The ordinary interest on a $18,500 loan at 10.5% interest for 90 days is $486.04.
Step-by-step explanation:
To calculate the ordinary interest, we can use the formula:
Interest = Principal × Rate × Time
Given that the principal is $18,500, the rate is 10.5%, and the time is 90 days (or 0.25 years), we can substitute these values into the formula:
Interest = $18,500 × 0.105 × 0.25 = $486.04
Therefore, the ordinary interest you would pay on a $18,500 loan at 10.5% interest for 90 days is $486.04, which corresponds to option b.