Question

Deana invests some money that earns interest compounded annually. At the end of the first year, she earns $400 in interest. At the end of the second year, she earns $432 in interest.
a) what interest rate, compounded annually, is deana earning?
b) how much did she invest?

Answer 1

I think you can do the following:

P*R=I

Where

P=principal=amount investere
R=interest rate
and
I=amount in interest

You have two equations.

1.)

P*R=400

and

(P+400)*R=432

****The principal now includes the interest from the previous year.

Solving for P (Equation 1):

P=400/R

Plug into equation 2, and solve for R:

(400/R+400)*R=432

400+400R=432

400R=32

R=32/400

R=0.008=0.8%

You know R, so solve for P:

Using equation 1:

P=400/R

P=400/0.008

P=$50,000

Answer 2

Fixed a typo: Look for #%^

I think you can do the following:

P*R=I

Where

P=principal=amount invested (#$^)
R=interest rate
and
I=amount in interest

You have two equations.

1.)

P*R=400

and

(P+400)*R=432

****The principal now includes the interest from the previous year.

Solving for P (Equation 1):

P=400/R

Plug into equation 2, and solve for R:

(400/R+400)*R=432

400+400R=432

400R=32

R=32/400

R=0.008=0.8%

You know R, so solve for P:

Using equation 1:

P=400/R

P=400/0.008

P=$50,000

Answer 3

Iu

Answer 4

I'm sorry, I'm not sure what you mean by "Iu." Can you please provide more context or information?