suppose you invest some money that grows to the amount A(t)=1000*2^(t/10) in t years

a. how much money did you invest?

b. how long does it take to double your money?

Question

suppose you invest some money that grows to the amount A(t)=1000*2^(t/10) in t years

a. how much money did you invest?

b. how long does it take to double your money?

anonymous · Answer

$$A(t)=1000(2)^{t/10}?$$

anonymous · Answer

yes

anonymous · Answer

a) The money that first invested is that at t=0, that's:
$$A(0)=1000(2)^{0/10}=1000$$

anonymous · Answer

b)To double this amount, that's to make it 2000:
$$1000(2)^{t/10}=2000 \implies 2^{t/10}=2 \implies {t \over 10}=1 \implies t=10$$
So, the money will be doubles after 10 years.. Long time I know :P

anonymous · Answer

why do you use a 0 in the t spot

anonymous · Answer

Because part a) is asking about the money that you invested at the "beginning", that's at time t=0. So, I plug t=0. Does that make sense?

anonymous · Answer

yes thank you

anonymous · Answer

You're welcome!!