monthly repayments (1 Viewer)

[donrob15]

can someone please tell me how to do this question? ( b part ii)

An=200000(1.006)^(n) - 2800 [ (1+1.006+1.006^2 + 1.006^3 +....+1.006^(n-1) ]

I got as far as An = 0 and rearanged a bit, but didnt know where to go from there. Any help would be great as I may need to know how to do somthing like it ext1.

 

[mbenson]

can someone please tell me how to do this question? ( b part ii)

An=200000(1.006)^(n) - 2800 [ (1+1.006+1.006^2 + 1.006^3 +....+1.006^(n-1) ]

I got as far as An = 0 and rearanged a bit, but didnt know where to go from there. Any help would be great as I may need to know how to do somthing like it ext1.

in your eqn above there is a G.S. (a=1, r=1.006, n=n); and you solve for An = 0

Sn = [{(1.006^n)-1}/0.006]
.: 2800[(1.006^n)-1] = 1200(1.006^n)

==> 2800(1.006^n) - 2800 = 1200(1.006^n)
==> 1600(1.006^n) = 2800
==> 1.006^n = 1.75
==> ln(1.006^n) = ln 1.75
==> n ln (1.006) = ln 1.75
==> n = (ln 1.75)/(ln 1.006)
.: n = 93.5488...
.: 94 monthly repayments of $2800

hope that refreshes your brain ( i do 2U so im guessing you already knew how to do that)
good luck

 

[donrob15]

thanks nbenson

i couldnt figure it out because i forgot that fundamental ln rule of brining down the power and putting it in front of the ln. thanks heaps. good luck to you as well.

 

[dunno04]

i got....1430..around that
ANd 116...

I guess i am wrong.
DAmmit.
><

 

[lissamaher]

I got 93.5 for my n
For the first part i got $1439.18

 

[shinji]

d'you rekkon they'd let it go if u were like 1-2 repayments off? lol

coz im pretty sure i got 96 or sumin~~ :S

 

[k8kate]

this qu shitted me so much. I kept trying to log a negative number about 500 times. then redid the qu 500 more times in about 2 booklets and somehow got .24 months.

I gave up

 

[kido_1]

I got 94 months, using exact value in the end the exact answa is like In(1.75)/In(1.006)

 

[thehootman]

I got the first part, but screwed up the second part by doing something silly...ended up solving it by reducing to quadratics....gave me the wrong answer of 88 months....94 is the answer

 

[dunno04]

well...
i think i got some calculation problem.
dam clumsy mistakes
....
Ohh Gawd