Algebra
posted by Sylvie .
Show how you substitute the values into the formula, then use your calculator.
*Use A = P(1+r/n)nt to find the amount of money in an account after t years, compounded n times per year.
*Use I = Prt to find the amount of simple interest earned after t years
1) If a person invests $5780 in an account that pays 9% interest compounded annually, find the balance after 13 years.
I got A = 5780 (1+0.09/1)13, but my calculator answer doesn't seem right.
2) Find the value of $3500 deposited for 9 years in an account paying 5% annual interest compounded semiannually.
3) Find the value of $1200 deposited for 18 years in an account paying 7% annual interest compounded monthly. I got A = 1200(1+.07/12)216, but again, I don't know how to use the calculator for this.
4) Find the amount of simple interest earned if you invest $9000 at .04% interest for 20 years. Then find the account balance.

1. Your expression is correct, I got 17720.35
(this might seem high, but true. Back in the "olden days" before calculators we used something called the rule of 72. It meant if you have a time and rate which multiplied to something close to 72, your money would double.
e.g. at 8% money would double in appr 9 years (9x8=72)
e.g. 100(1.08)^9 = 199.90
in your case it would have doubled in 8 years to appr. 11560 , which would reach 23120 after 18 years.
So 17720 after 13 years is reasonable.
2. amount = 3500(1 + .05/2)^(9(2))
= 3500(1.025)^18 = 5458.81
3. your expression is correct again, perhaps you don't know how to use your calculator
the magic key is the y^{x} key
e.g. to do 4^3
enter 4
press the y^{x} key
enter 3
press =
you should get 64
so for A = 1200(1+.07/12)^216
here are my keystrokes
.07 ÷12
=
+1
=
y^{x}
216
= > at this point you should have 3.5125...
x
3500
=
you should get 12293.89
Respond to this Question
Similar Questions

math
The amount of money in an account with continuously compounded interest is given by the formula A = Pert, where P is the principal, r is the annual interest rate, and t is the time in years. Calculate to the hundredth of a year how … 
math
If $7,800 is depostied into an account paying 6% interest compounded annually ( at the end of each year), how much money is in the account after 2 years? 
math
If $5,600 is deposited into an account paying 5% interest compounded annually (at the end of each year), how much money is in the account after 3 years? 
Calc
A person deposits money into a retirement account, which pays 7% interest compounded continuously, at a rate of $1000 per year for 20 years. Calculate: a. The balance of the account at the end of 20 years b. the amount of money actually … 
Algebra
Use the compound interest formula $18,000 is invested in an account paying 3% interest compounded quarterly. Find the amount of money in the account at the end of 10 years. (Show values substituted in the formula, and calculate the … 
Math
Use the compound interest formula to solve: $18,000 is invested in an account paying 3% interest compounded quarterly. Find the amount of money in the account at the end of 10 years. (Show values substituted in the formula, and calculate … 
Precalculus
NEED HELP ASAP PLEASE!! A savings account starts with $600 and pays 5% interest per year, compounded four times per year. a) A function that models the amount in dollars in the bank account after m years is A(m)=____________? 
math
Suppose that you have $12,500 to invest over a 4 year period. There are two accounts to choose from: 4.5% compounded monthly or 4.3% compounded continuously. a. Write the formula for the first account’s compound interest for n compounding … 
algebra
To find the amount A in an account after t years with principal P and an annual interest rate r compounded continuously, you can use the formula 
algebra
Compound interest word problem. Suppose JJ has $1000 that he invests in an account that pays 3.5% interest compounded quarterly. How much money does JJ have at the end of 5 years?