Question: how to find time in a compound interest problem?
Answer: Calculate Accrued Amount (Principal + Interest) A = Pert
Calculate Principal Amount, solve for P. P = A / ert
Calculate rate of interest in decimal, solve for r. r = ln(A/P) / t.
Calculate rate of interest in percent. R = r * 100.
Calculate time, solve for t. t = ln(A/P) / r.