how long does it take $1125 to triple ($3375) at 7% that compounds quarterly (3 months)??

Answer 1

This is a math problem, not chemistry.
So 7% is annual rate and the interest compounds 4 times a year. So the interest rate for a quarter is:
(1 + 7%)^(1/4) - 1 = 1.706%
The question is now reduce to ask what is n in the equation:
(1 + 1.706%)^n = 3
n* log(1 + 1.706%) = log(3)
n = log(3)/log(1.01706) = 65
It takes 65 quarters for any principle to triple at 7% fixed annual rate.