Answered

A sum of money becomes ` 17640 in two years and ` 18522 in 3 years at the same rate of interest, compounded annually. Find the sum and the rate of interest per annum.



Answer :

Answer:

Let's denote the principal amount as \( P \) and the annual interest rate as \( r \) (in decimal form).

The compound interest formula is given by:

\[ A = P \left(1 + \frac{r}{n}\right)^{nt} \]

where:

- \( A \) is the amount after \( t \) years,

- \( n \) is the number of times interest is compounded per year (for annual compounding, \( n = 1 \)),

- \( t \) is the time in years.

In this case:

1. After 2 years, \( A_2 = 17640 \),

2. After 3 years, \( A_3 = 18522 \).

For 2 years:

\[ 17640 = P \left(1 + \frac{r}{1}\right)^{1 \times 2} \]

For 3 years:

\[ 18522 = P \left(1 + \frac{r}{1}\right)^{1 \times 3} \]

Now, we have a system of two equations with two unknowns (\( P \) and \( r \)). You can solve this system of equations to find the values of \( P \) and \( r \). The solution will give you the principal amount and the annual interest rate.