Answer:
9.9 years
Explanation:
A = P e ^(rt)
Where A is the amount in the account
P is the amount invested
R is the interest rate
t is the time
P = 8500
r =7% = .07
A = 17000
Substituting into the equation
17000=8500 e^(.07t)
Divide each side by 8500
17000/8500=8500/8500 e^(.07t)
2 = e^(.07t)
Take the natural log of each side
ln (2) = ln e^(.07t)
ln(2) = .07t
Divide each side by .07
ln(2)/.07 = .07t/.07
ln(2)/.07 = t
9.902102579=t
Rounding to one decimal place
9.9 years