Question 1100133
If a painting costs $3500, and the value increases by 15% a year, 
in how many years will the value be twice its original cost? 
:
let t = years to double paintings value
:
3500*(1.15)^t = 7000
Divide both sides by 3500
1.15^t = 2
use natural logs here
t*ln(1.15) = ln(2) 
t = {{{ln(2)/ln(1.15)}}}
t = 4.96 ~ 5 yrs to double the value