Attendance at the Fireman's Ball has been declining. Each Year, the number attending is 2/3 of the previous year's attendance.
In what year will the attendance be less than 1/3 the original attendance?
(2/3)^N = 1/3
I recommend use logs
Nlog2-Nlog3=log1-log3
N(log2-log3)=0-log3
solve for N.