SOLUTION
From the question
The principal is $6500
a. The equation needed to calculate the compound interest is
Where
A = amount earned
P= principal
r= rate
t= time
b. Give:
t= 10 years
r = 3.7%
Substitute the values into the compound interest formula:
Calculate the value of A
Hence the value of the account after 10 years is $9347.62
c. substitute t=20 into the formula
Solve for A
Therefore the value of the account after 20 years is $13442.76
Since the account value after 20 is $13442.76 and the value earned over 10 years is $9347.62 then the extra interest earned is
Therefore He earned $4095.14 more in interest