Rui Feng deposited $15,000 in an account that pays 5.68% compound interest per year. Find the total amount in the account after 6 years if the interest is compounded:

(a) Monthly
(b) Half-yearly



Answer :

Certainly! Let's break down the problem and find the total amount in Rui Feng's account after 6 years under different compounding conditions.

Given:
- Principal ([tex]$P$[/tex]): [tex]$15,000 - Annual Interest Rate ($[/tex]r[tex]$): 5.68% - Number of Years ($[/tex]t[tex]$): 6 years We will use the compound interest formula: \[ A = P \left(1 + \frac{r}{n}\right)^{nt} \] Where: - \( A \) = the amount of money accumulated after n years, including interest. - \( P \) = the principal amount (the initial amount of money). - \( r \) = annual interest rate (decimal). - \( n \) = number of times the interest is compounded per year. - \( t \) = number of years the money is invested. ### Part (a): Compounded Monthly For monthly compounding: - The interest is compounded 12 times a year (\( n = 12 \)). - The annual interest rate \( r \) is 5.68%, which is 0.0568 in decimal form. Plugging the values into the compound interest formula: \[ A_{\text{monthly}} = 15000 \left(1 + \frac{0.0568}{12}\right)^{12 \times 6} \] Using this formula, we find: \[ A_{\text{monthly}} = 15000 \left(1 + \frac{0.0568}{12}\right)^{72} \] After solving this expression, the total amount in the account after 6 years, if the interest is compounded monthly, is approximately: \[ A_{\text{monthly}} \approx 21,074.13 \] ### Part (b): Compounded Half-yearly For half-yearly compounding: - The interest is compounded 2 times a year (\( n = 2 \)). - The annual interest rate \( r \) remains 0.0568 in decimal form. Plugging the values into the formula: \[ A_{\text{half-yearly}} = 15000 \left(1 + \frac{0.0568}{2}\right)^{2 \times 6} \] Using this formula, we find: \[ A_{\text{half-yearly}} = 15000 \left(1 + \frac{0.0568}{2}\right)^{12} \] After solving this expression, the total amount in the account after 6 years, if the interest is compounded half-yearly, is approximately: \[ A_{\text{half-yearly}} \approx 20,991.14 \] ### Summary: 1. The total amount in Rui Feng's account after 6 years with monthly compounding is approximately $[/tex]21,074.13.
2. The total amount in Rui Feng's account after 6 years with half-yearly compounding is approximately $20,991.14.