Q:

45 Points!!!!!!!!!!!!!!Alexander deposited money into his retirement account that is compounded annually at an interest rate of 7%. Alexander thought the equivalent quarterly interest rate would be 2%. Is Alexander correct? If he is, explain why. If he is not correct, state what the equivalent quarterly interest rate is and show how you got your answer.

Accepted Solution

A:
The equation for compound interest is:

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

Where r is the interest rate and n is the number of times per year it's applied.
Β 
Annually n = 1 and 7% interest r = 0.07
The quarterly rate 2% is already quartered 0.02 = r/n .

[tex](1+0.07)= (1+0.02 ) ^{4} \\ \\ 1.07 = (1.02) ^{4} \\ \\ 1.07 \neq 1.082 [/tex]

You can see that Alexander is incorrect. A quarterly compound interest rate of 2% will accrue more interest than a 7% compound annual interest rate.

[tex] (1+0.07) = (1+ r) ^{4} \\ \\ 1.07 = (1+r) ^{4} \\ \\ \sqrt[4]{1.07} = r \\ \\ \sqrt[4]{1.07} - 1 = r \\ \\ r = 0.017 [/tex]

1.7% compound quarterly