SOLUTION: please help me slove this problem Slove the problem. Find out how long it takes a $3000 investment to double if it is invested at 8% compounded semiannually. Round to the neare

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Question 122036: please help me slove this problem
Slove the problem. Find out how long it takes a $3000 investment to double if it is invested at 8% compounded semiannually. Round to the nearest tenth of a year. Use the formula
A=P(1+r/n)^nt
possible anwsers
1.) 8.8 years
2.) 9.2 years
3.) 9 years
4.) 8.6 years
thank you for your help
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
P+=+3000
r+=+.08
n+=+2 (n is the number of times per year interest is compounded)
A+=+6000 (A is the amount after t years. The problem
wants to know what t is when A+=+2P)
A+=+P%281+%2B+r%2Fn%29%5Ent
6000+=+3000%281+%2B+.08%2F2%29%5E%282t%29
divide both sides by 3000
2+=+%281+%2B+.04%29%5E%282t%29
2+=+1.04%5E%282t%29
Take the log to base 10 of both sides
log%282%29+=+2t%2Alog%281.04%29
.30103+=+2t%2A.01703
t+=+.30103+%2F+.03406
t+=+8.8382 years
That's approximately (1) 8.8
This is 8 years + .8382%2A12+=+10.059 months
And this is 8 years, 10 months .059%2A30+=+2 day
The answer is 8 years 10 months 2 day
Unless I made a mistake, that is.