Question

Initial investment:$750
Annual rate:?
Time to double: 7 and 3/4 yrs
Amount after 10 yrs:?
Using the formula A=Pe^rt, find the annual rate, and amount after 10 years..
thanks so much!!! please explain!!

Answer 1

A = Accumulated amount
P = Start amount
r = annual rate
t = time.

This should help you solve the question.

Answer 2

You'll learn a lot more by doing it :)

Answer 3

A=750e^r(10)
thats how far i got.. dont know what do to now

Answer 4

You first need to solve r.

They tell you it doubles in 7 and 3/4 years.

They give you P (the initial value) and they also give you A (indirectly)

So you have A, t, and P. solve r.

Once you have r, you'll be able to solve the second part of the question

Answer 5

so i just dont know what A is then...?

Answer 6

To get the A after 10 years, you do that which you said previously:

A=750e^r(10)

BUT

You don't know what r is yet. So the only way to solve r, is to find out at which interest rate the 750 doubled in 7 and 3/4 years. To find this, plug those value into the formula. After you find the r, you can find the amount after 10 years

Answer 7

oh so 1500=750e^r(7and3/4)?

Answer 8

yes!

Answer 9

so the answer to this is the rate?

Answer 10

Yep. r is the rate

Answer 11

so after this would the A be 1500 as well???

Answer 12

No. r is a constant. So, once you get r, you plug it into this:

A=750e^r(10)

Answer 13

ok so i got 9.22
A=750e^9.22(10)
now do you just divide 750, then do the LN?

Answer 14

or you just times everything..i think

Answer 15

How did you get 9.22? You sure about that? Just recheck, show me what you did, something went wrong

Answer 16

1500=750e^r(7and3/4)
divide 750
2=e^r(7 and 3/4)
take Ln
LN 2=r(7and 3/4)
divide by 7.75
Ln 2/7.75
=0.0894383

Answer 17

Yes, thats correct. Now remember, when you use that in the formula, you should use 0.0894383.

It is 8.94383%, but if used in calculation, it should be 0.0894383.

Now you can solve for A!

Answer 18

wait so do i use 8.94383? or the other?

Answer 19

so it would be A=750e^0.0894383(10)??

Answer 20

Yep

Answer 21

Thank you so much!!
You are AMAZING!!
This helped tons!!

Answer 22

Shot, glad to help! Shout out if you need anything else.

Answer 23

Will do thanks:)