Answer:
Account B earns more interest.
After 20 years, account B will have earned $171.89 more.
Step-by-step explanation:
Let's calculate the total for each account.
Account A:
Account A earns simple interest. We know that the principal value is $2000 and the interest rate is 2% or 0.02. We can use the simple interest formula:
![A=P(1+rt)](https://tex.z-dn.net/?f=A%3DP%281%2Brt%29)
Where A is the future value, P is the principal, r is the rate, and t is the time in years.
So, let's substitute 2000 for P, 0.02 for r, and 20 for t. This yields:
![A=2000(1+0.02(20))](https://tex.z-dn.net/?f=A%3D2000%281%2B0.02%2820%29%29)
Multiply and add:
![A=2000(1+0.4)=2000(1.4)](https://tex.z-dn.net/?f=A%3D2000%281%2B0.4%29%3D2000%281.4%29)
Multiply. So, the total amount of money in Account A after 20 years is:
![A=\$2800](https://tex.z-dn.net/?f=A%3D%5C%242800)
Since we initially deposited $2000 and our total is now $2800, this means that we earned an interest of ![2800-2000=\$ 800](https://tex.z-dn.net/?f=2800-2000%3D%5C%24%20800)
Account B:
Account B earns compound interest. Like Account A, Account B has a principal value of $2000 and the interest rate is 2% or 0.02. We also know that it's compounded annually, so once per year. We can use the compound interest formula:
![B=P(1+\frac{r}{n}})^{nt}](https://tex.z-dn.net/?f=B%3DP%281%2B%5Cfrac%7Br%7D%7Bn%7D%7D%29%5E%7Bnt%7D)
Where B is the future value, P is the principal, r is the rate, n is the times compounded per year, and t is the time in years.
So, let's substitute 2000 for P, 0.02 for r, n for 1 (since it's compounded annually), and t for 20. This yields:
![B=2000(1+\frac{0.02}{1})^{(1)(20)}](https://tex.z-dn.net/?f=B%3D2000%281%2B%5Cfrac%7B0.02%7D%7B1%7D%29%5E%7B%281%29%2820%29%7D)
Simplify this to acquire:
![B=2000(1.02)^{20}](https://tex.z-dn.net/?f=B%3D2000%281.02%29%5E%7B20%7D)
Evaluate. Use a calculator. So, after 20 years, the amount of money in Account B is:
![B\approx\$2971.89](https://tex.z-dn.net/?f=B%5Capprox%5C%242971.89)
Since our principal was $2000, this means that we earned an interest of approximately
.
So, Account A earned an interest of $800 and Account B earned an approximate interest of $971.89.
So, Account B earned more interest.
And it earned
more than Account A.
And we're done!