<PRE><B>Question 1104667</B>
P=Poe^rt is the formula, P principal end, Po principal beginning, r is rate (decimal) and t time in years
11700=5850*e^(.095*t)
divide by 5850 both sides
2=e^.095t
ln both sides
ln2=0.095 t
divide by 0.095 both sides 
7.30 years. ANSWER
Rule of 70 would say doubling occurs when  rate (per cent)*time=70
That is an approximation but holds here.
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