Answer:
The minimum amount of time required is:
26.82 years.
Explanation:
Present value = $2,600
Future value = $7,800 ($2,600 * 3)
Annual interest rate = 4.1%
Monthly interest rate = 4.1%/12 = 0.342%
$2,600 will need to be invested for 321.781 (26.82 years) periods to reach the future value of $7,800.00.
FV (Future Value)	$7,800.00
PV (Present Value)	$2,600.00
N (Number of Periods)	321.781
I/Y (Interest Rate)	0.342%
PMT (Periodic Payment)	$0.00
Starting Investment	$2,600.00
Total Principal	$2,600.00
Total Interest	$5,200.00