Sequence and SEries Help (1 Viewer)

[Lukybear]

Jasmine deposists 600 into an account on the 1st December each year starting in 1995. She recieves an interest rate of 6% p.a. compounded annually.

How much will her total investment be worth by december 2008

How much interest has she recieved.

 

[addikaye03]

Jasmine deposists 600 into an account on the 1st December each year starting in 1995. She recieves an interest rate of 6% p.a. compounded annually.

How much will her total investment be worth by december 2008

How much interest has she recieved.

n=13, i=0.06 P=$600

A_1=600(1.06)^13 {So the first amount is in there for 13 years}

A_2=600(1.06)^12

A_3=600(1.06)^11

...

A_13=600(1.06)

.'. A_n=600(1.06)+600(1.06)^2+600(1.06)^3+..+600(1.06)^13

Geometric: a=600(1.06), r=1.06

Sn=600(1.06)[(0.06)^13-1]/0.06

See what i done OP? So the first amount is compunded for 13 yrs, second is compounded for 12, third amount for 11, creating a geometric progression

 

[Lukybear]

Are you sure its 13? The problem i have is knowing how many yrs its presented. Cause it starting 1st december, and finish by december 2008. So shouldnt A1 = 600(1.06)^12?

 

[Lukybear]

Or to put it more simply, my question is when does interest get calculated? If its annually, is it the first day of input?

 

[addikaye03]

Or to put it more simply, my question is when does interest get calculated? If its annually, is it the first day of input?

Well obviously interest isn't calculated if you put it in the day off

So 96,97,98,99,00,01,02,03,04,05,06,07,08

It does say "total investment be worth by december 2008" so 08 would be included

Like if you let my "A_1 be 2008" then count backwards "A_2 be 2007" then you get "A_13=1996" which would be the first year that interest would be inclusive.

So i believe it is right, i may be wrong but i dont think so... i never did like the wording of these Q though

 

[Lukybear]

Yea their terrible. But i did the workings according to 13 terms, and i got 600 off. Like 600 too many...

 

[addikaye03]

Yea their terrible. But i did the workings according to 13 terms, and i got 600 off. Like 600 too many...

hmm so a=600(1.06)^0, so must be 12... i swear in that instance 13 makes sense though

 

[Lukybear]

Yea, but it isnt, 12 either. Youll get 11329.2826 which is way off. I am thinking, its 13, but without the last added 600. So itll be 600(1+1.06+1.06^2...1.06^13) - 600. Is there anykind of q like that?

 

[addikaye03]

How much interest has she recieved.

Ahh lol!!! i didn't read that previously. That might explain the answer.

Interest=Total-Amount input

So i'm guessing that since she put it $600 every year, it would be (-600 times the amount of times she put $600 in)

So it would be -12(600) since she wouldn't put more in in 2008

So i still think its 13:

Interest=A_13 - 12(600)

 

[Lukybear]

Yea mabey. THe wording isnt thata good i recon.

BTW, if your not busy, help me with my locus q.

 

[addikaye03]

Yea mabey. THe wording isnt thata good i recon.

BTW, if your not busy, help me with my locus q.

yeah no worries, post it up and i'll help you out