Question

Use a arithmetic sequence, arithmetic series, geometric sequence, or geometric series to solve? DO not need to solve just which formula should I use? Thanks!
Jackie deposited $5 into a checking account in February. For each month following, the deposit
amount was doubled. How much money was deposited in the checking account in the month of
August?

Answer 1

Definately geometric series

Answer 2

I said geometric sequence.

Answer 3

I used this forula sn= a1-a1rn/1-r

Answer 4

Summation of 5(2)^n

Answer 5

An = 2*A{n-1}

Answer 6

actually question just asks how much was deposited in august, not total. so it is
\[5\times 2^6\] if i counted months correctly

Answer 7

oh yeah, then sequence if you don't want the accumulation

Answer 8

I came up with 320, but I don't need to submit this answer just the formula.

Answer 9

An = 2.2.A{n-2}
= 2.2.2.A{n-3}
= 2^r . A{n-r}
when r = n; we get to A{0}

An = 2^{n}. A{0} or did i mess it up somewhere?

Answer 10

how much was the deposit in august or how much in total has been depostited?

Answer 11

Are we in agreement that it is a geometric sequence since I only need to know August and not the total sum?

Answer 12

geo if we only want to know the amount for augusts deposit

Answer 13

you lost me
it is
feb mar apr may june july aug
5, 10, 20, 40, 80, 160, 320

Answer 14

yes geometric
\[5, 5\times 2, 5\times 2^2, 5\times 2^3, ...\]

Answer 15

m: f m a m j j a
n: 0 1 2 3 4 5 6
A: 5 10 20 40 80 160 320

Answer 16

geometric sequence

Answer 17

Thanks. Great conversation!

Answer 18

i tend to start at a0 instead of a1 :)