Posted by **Hannah** on Tuesday, February 9, 2010 at 3:50pm.

1) initial investment = $600

annual % rate = ?

time to double = ?

amount after 10 years = $19,205.00

19,205 = 600e^(10r)

I do not know how to solve for r of find the time to double.

- (Please help) Math -
**drwls**, Tuesday, February 9, 2010 at 4:33pm
That looks like a misprint, but if the investment really increased that fast,

19,205 = 600 (1 + r)^10

10 ln (1+r) = ln (19,205/600) = ln 32.0

= 3.4657

ln (1+r) = 0.34657

1+r = 1.414

r = 41.4%

The time to double is 2.0 years

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