need help w/interest word problem?

2000(1 + 0.05/365)^(365n) = 6000

(1 + 0.05/365)^(365n) = 3

365n ln(1 + 0.05/365) = ln(3)

n = ln(3)/[365ln(1 + 0.05/365)]

= 21.97375069

≈ 22 years .....approximately

Financial institutions typically calculate amortizations based on 30 day months and 360 day years for simplicity. Using those assumptions your future value calculation becomes:

6000 = 2000(1+r/n)^(nt)
where:
r = annual interest rate
n = number of compounding periods per year (360 for daily compounding)
t = number of years

3 = (1+.05/360)^(360t)
3 = (360.05/360)^(360t)
log3 = 360t log(360.05/360)
t = log3/[360log(360.05/360) = 21.97

Ans: About 10 days short of 22 years

t = ( log (x) / log (1 + i)) / n

t = time in years
x = 2 (double), 3 (triple), etc.
i = effective interest rate = annual rate / payment frequency
n = payment frequency (1 yearly, 4 quarterly, 12 monthly, etc.)

Rules of thumb:

double money time = 72 / annual rate
triple money time = 115 / annual rate

so for 5% you should arrive at around 23 years to triple using the first formula above

Using rule of 72; about 43 years. A more exact answer your need to look annuity tables.

199 years