Posted by **tasha** on Thursday, February 19, 2009 at 9:32am.

find out how long it takes a $2700 investment to double if it is invested by 7% compounded semiannually. Round to the nearest tenth of a year . Use the formula A=P[1+r/n]^nt

- math-help solve please -
**bobpursley**, Thursday, February 19, 2009 at 9:38am
2=(1+.07/2)^2t

log of both sides..

log2=2t log(1+.035)

can you do that? Solve for t?

- math-help solve please -
**Reiny**, Thursday, February 19, 2009 at 9:39am
you want the $2700 to double, so A = 5400

5400 = 2700(1 + .035)^(2t)

2 = 1.035^(2t)

I hope you know how to use logs and know the rules of log operations

2t = log 2/log 1.035

2t = 20.148

t = 10.07

= 10.1 to the nearest tenth

- math-help solve please -
**tasha**, Thursday, February 19, 2009 at 9:55am
how did you get (.035)

- math-help solve please -
**bobpursley**, Thursday, February 19, 2009 at 10:12am
seven percent/n= .07/2

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