From the given data : P = $12,000 and r = 3.5%.
\r =
.
Formula for continuous compounding :
.
Compounding per 10 years, the balance is : \ \
\
Compounding per 20 years, the balance is :
\
Compounding per 30 years, the balance is :
\
Compounding per 40 years, the balance is :
\
Compounding per 50 years, the balance is :

The table for compound interest is :
\| t | \10 | \ \
20 \ | \
\
30 \ | \
\
40 \ | \
50 | \
| \
A \ | \
\
$17028.81 \ | \
\
$24165.03 \ | \
\
$34291.81 \ | \
\
$48662.4 \ | \
\
$69055.23 \ | \
The table for compound interest is : \ \
\| t | \10 | \ \
20 \ | \
\
30 \ | \
\
40 \ | \
50 | \
| \
A \ | \
\
$17028.81 \ | \
\
$24165.03 \ | \
\
$34291.81 \ | \
\
$48662.4 \ | \
\
$69055.23 \ | \