How to use interpolation method to calculate interest rate Given the coefficient of present value (or final value) of annuity and the number of periods n, it is a little unclear when calculating the interest rate according to the interpolation formula Example: a company borrows 20000 yuan at the beginning of the first year, and repays 4000 yuan at the end of each year, which is paid off for nine consecutive years? （P/A,i,9)=P/A=20000/4000=5 When I = 12%, (P / A, 12%, 9) = 5.3282; I = 14%, (P / A, 14%, 9) = 4.9464 So I = 12% + (5.3282-5) / 5.3282-4.9464) * (14% - 12%) = 13.72% The formula I = I1 + (b-b1) / (b2-b1) * (i2-i1), why not I = 12% + (5-5.3282) / 4.9464-5.3282) * (12% - 14%) How to define I1 and I2 in the formula? Which of the 12% and 14% in the above example is I1 and which is I2?

How to use interpolation method to calculate interest rate Given the coefficient of present value (or final value) of annuity and the number of periods n, it is a little unclear when calculating the interest rate according to the interpolation formula Example: a company borrows 20000 yuan at the beginning of the first year, and repays 4000 yuan at the end of each year, which is paid off for nine consecutive years? （P/A,i,9)=P/A=20000/4000=5 When I = 12%, (P / A, 12%, 9) = 5.3282; I = 14%, (P / A, 14%, 9) = 4.9464 So I = 12% + (5.3282-5) / 5.3282-4.9464) * (14% - 12%) = 13.72% The formula I = I1 + (b-b1) / (b2-b1) * (i2-i1), why not I = 12% + (5-5.3282) / 4.9464-5.3282) * (12% - 14%) How to define I1 and I2 in the formula? Which of the 12% and 14% in the above example is I1 and which is I2?

Just say I'm afraid I can't make it clear, try it! You first draw a line segment, and then add a point in the middle. At this time, there are three points. You write 5.3282, 5, 4.9464 on the three points above the line, 12%, X%, 14% on the corresponding points below the line (note that the corresponding order is correct), and then take up the total line segment by one paragraph