Naomi deposited money into a savings account that is compounded quarterly at an interest rate of 6%. She thinks this quarterly rate is the same as a monthly interest rate of 1.25%. Is Naomi right? If so, explain why and show how you got your answer. Is Naomi incorrect? If so, explain the mistake in her reasoning, give the correct monthly interest rate, and show how you got your answer. Please help me!! It’s due today

Respuesta :

We know that the Compound Interest Formula is given as:

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

Where A is the amount,

P is the Principal,

r is the interest rate in decimal

n is the number of times interest is compounded per year

t is the number of years.

In our case we will have to find the Amount, A in one year when the principal, P is compounded quarterly at a rate of 6% and compare it with the amount when the same principal is compounded monthly at a rate of 1.25% monthly and see if they are equal or not and explain the possible reason.

Let us begin:

Case 1

6% Quarterly

[tex]A=P(1+\frac{0.006}{4})^{4\times 1}=P(1+0.0015)^4\approx1.006P[/tex]

Case 2

1.25% Monthly

[tex]A=P(1+\frac{0.0125}{12})^{12\times 1}=P(1+0.00104167)^{12}\approx1.0126P[/tex]

As we can clearly see the first case gives us 1.006P and the second case gives us 1.0126P.

Therefore, Naomi is incorrect in her reasoning. This can be seen from the fact that the [tex]\frac{r}{n}[/tex] and the [tex]n\times t[/tex] are coming out to be different for both the cases and thus effecting the overall results.