Q:

Noah currently has an account balance of $2,976.45. He opened the account 11 years ago with a deposit of $1,963.45. If the interest compounds quarterly, what is the interest rate on the account?

Accepted Solution

A:
What we know:
Acct. balance A (11)= $2,976.45
Pricipal=$1,963.45
Compounded (n)=quarterly (4)
rate=r
Compound interest formula: A (t)=p (1+r/n)^nt

What we need toi find:
If the interest compounds quarterly, what is the interest rate on the account? Find r.
A (t)=p (1+r/n)^nt
2976.45=1963.45 (1+r/4)^(4×11)
2976.45=1963.45 (1+r/4)^44
2976.45/1963.45=1963.45/1963.45 (1+r/4)^44
1.5159=(1+r/4)^44
(1.5159)^(1/44)=((1+r/4)^44)^(1/44)

1.0095=1+r/4
1.0095-1=1-1+r/4
.0095=r/4
.0095(4)=r/4 (4)
.038=r

Rate = 3.8%