Math
posted by tania .
if $15,000 is invested at 6%, compounded quarterly, how long will it be before it grows to $25,000?

25000 = 15000(1.015)^n , where n is the number of quarter years
5/3 = 1.015^n
log both sides
log (5/3) = log (1.015^n)
log5  log3 = n log 1.015
n = (log5  log3)/log 1.015 = appr 34.3 quarters
or 11.4 years or 137 months