Landon opened a savings account with a deposit of $3,786.45. Nine years later, the balance in the account is $5,135.29. If the interest rate is 3.4%, how often does the interest compound?

Question

anonymous · Answer

why did it go away?

akashdeepdeb · Answer

I deleted it!
I was on the wrong track! :D O.O

anonymous · Answer

Haha okayy.

akashdeepdeb · Answer

Tag someone!

anonymous · Answer

how?

akashdeepdeb · Answer

@ 'And then their username'

amistre64 · Answer

a good formula to use would be the compounding formula:

A = P(1+r/n)^(nt)

amistre64 · Answer

A = Pk^(9n)

A/P = k^(9n)

ln(A/P) = 9n ln(k)

ln(A/P)/9ln(k) = n

ln(A/P)/9ln(1+r/n) = n

this at least gives us a resurrsion setup that we can trial and error by making a guess

n = ln(A/P)/9ln(1+r/g) ; each new value for n the we get we plug in got "g" and recalculate ... it should get us closer and closer to the true value of n

amistre64 · Answer

of $3,786.45. Nine years later, the balance in the account is 5135.29. If the interest rate is 3.4%, h

ln(5135.29/3786.45)/(9ln(1+.034/g))

i guessed at 12 and it crept down
i guessed at 2 and it crept up
i guessed at 6 and it crept down

it has to be between 2 and 6

i guessed at 4 and it barely creeping .... lets assume 4 is good

amistre64 · Answer

3786.45(1+.034/4)^(9*4) = 5135.2869...

amistre64 · Answer

i spose we could have trial and errored it without the formula ... but you know :)