If you have 2500 to invest at 6 interest compounded quarterly. for how many years will the money need to be invested for that amount to triple?

For this case we have the following equation:
 P (t) = P * (1 + r / n) ^ (n * t)
 Where,
 P: initial investment
 r: interest rate
 n: periods
 Substituting values:
 3 * 2500 = 2500 * (1 + 0.06 / 4) ^ (4 * t)
 Rewriting:
 3 = (1,015) ^ (4 * t)
 Clearing t:
 log1.015 (3) = log1.015 ((1.015) ^ (4 * t))
 4 * t = log1.015 (3)
 t = (1/4) * log1.015 (3)
 t = 18.45 years
 
 the money will need to be invested 18.45 years for that amount to triple

The answer is