How do you compare Diminishing Interest to Float Interest?

Answer 1

You have confused between the terms. Simple interest and interest at flat rate is one and the same. The other type of interest is diminishing balance or reducing balance. These are interests associated with loans or finances sought. Well a simple rule of thumb is that usually simple interest rate is about half of rate on reducing balance. For e. g. if rate at reducing balance is 12% then simple interest for the same will be around or just more than 6%