Answer:
6.32 years
Step-by-step explanation:
To get the time taken to triple the amount invested, we must first establish the compound interest formula. When a principal amount P is invested for a time n at a rate r percent, the amount A after n years may be expressed as
A = P (1 + r)^n
Hence if $1,225 is to triple, the amount will be
= $1,225 *3
= $3,675
The time n for this to happen may be computed through the equation
$3,675 = $1,225 ( 1 + 0.19)^n
3 = 1.19^n
take the log of both sides
log 3 = log 1.19^n
using the law of logarithms that log a^b = b log a
n log 1.19 = log 3
n = log 3 / log 1.19
n = 6.32 years
