Math homework 2021

Question

A man needed money to buy lawn equipment. He borrowed $700.00 for eight months and paid $53.95 in interest. What was the rate of interest?

Answer 1

753.95 = 700(1+r)^(8/12)

753.95/700 = (1+r)^2/3

cube both sides

(753.95/700)^3 = (1+r)^2= about 1.25

(1+r)^2 = 1.25

take square root of both sides

r = sqr(1.25) -1 = annual rate of interest= about 1.12-1 = .12 = 12% APR