Question 1112350: 1.you deposit $4000 at 7% interest, compounded monthly how many years will it take untill investments exceeds $9000
2.you invest your money at 12 % compound interest paid quarterly, when will it double in value
Found 2 solutions by Boreal, stanbon:
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! 9000=4000(1+.07/12)^12n, from formula P=Po(1+r/n)^nt
(9/4)=(1.005833)^12n
ln(9/4)=12n log (1.005833), without rounding that initially
12n=139.42, and without rounding, divide by 12 to get 11.62 years, rounding here.
Rule of 72 would say it would double in 10.3 years, so this makes sense.
P=Po(1+(.12/4)^4n, P/Po=2
2=(1.03)^4n
ln2=4n ln (1.03)
4n=23.44, n=5.86 years; rule of 72 would say 6 years.
Answer by stanbon(75887)  (Show Source):
You can put this solution on YOUR website! 1.you deposit $4000 at 7% interest, compounded monthly how many years will it take untill investments exceeds $9000
4000*(1+(0.07/12))^(12t) > 9000
(1.00583)^(12t) > 9000
12t > log9000/log1.00583
12t > 1566.29
time > 130.52 years
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2.you invest your money at 12 % compound interest paid quarterly, when will it double in value ?
2P = P(1+(0.12/4))^(4t)
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1.03^(4t) = 2
4t = log(2)/log(1.03)
4t = 23.45
t = 5.86 years
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Cheers,
Stan H.
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