Mathematica Eterna
Open Access

Abstract

Annuity interest rates and applications

Luiz Alberto Camargo, Pushpa Narayan Rathie and Prabhat Kumar Swamee

The implicit expression for interest rate (R) involving principal loan amount (P), monthly payment (M) and time period in months (T) is studied for historical approximations, exact infinite series solution involving two arbitrary parameters, H-function solution, approximations including for large values of T in terms of infinite series as well as involving Lambert’s W-function. A new approximation for R is obtained from the main result which resulted in better numerical values for R than that obtained by Cantrell (2007). Three numerical Tables for R are given in 7 Appendices along with mathematical derivations of several results derived in this paper.