determine whether the problem should be solved using the formula for an arithmetic sequence, arithmetic series, geometric sequence, or geometric series. Explain your answer in complete sentences. You do not need to solve.

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?

I don't know how to determine whether its a geometric or arithmetic

Question

determine whether the problem should be solved using the formula for an arithmetic sequence, arithmetic series, geometric sequence, or geometric series. Explain your answer in complete sentences. You do not need to solve.

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?

I don't know how to determine whether its a geometric or arithmetic

accessdenied · Answer

You would agree that arithmetic in general involves regular addition / a common difference,  and geometric in general involves multiplication (and sum if its a series) and a common ratio?

accessdenied · Answer

It sometimes helps to look at the first few cases, like induction.
  At first, Jackie deposits $5.00 into the account.
  Next month, it is doubled.  2x $5.00 or $10.00 was deposited.
  The following month, it is doubled once again.  2x 2x $5.00 or 2x $10.00 or $20.00

anonymous · Answer

so it would be geometric since it involves a ratio of 2

accessdenied · Answer

Yes.  :)

anonymous · Answer

and then it would also be a series?

anonymous · Answer

since you are adding along as the months go by

accessdenied · Answer

That's what I was thinking at first, but it feels like a bit of a language question.
  It asks for how much "how much (was deposited) in the checking account", which seems to me like the amount Jackie was putting in on the month.  That would just be a sequence...
  If it had said, "how much was in the account when Jackie made the last deposit" or the like, I think this sounds more like the cumulative.

Can you see what I mean there?

anonymous · Answer

Yeah i see its not asking how much she has in total in her account, it just wants to know how much she is adding. I think i"m understanding this better thanks!!

accessdenied · Answer

Glad to help!  :)

accessdenied · Answer

interesting this question has actually come up often in the past (wanted to see if it had come up and others had a different take) i found about 4 different posts of this q on OS with google. :p http://openstudy.com/study#/updates/4e43e2540b8b32e1c74cd785 one of those

anonymous · Answer

Well its nice to know that people got mixed up on the same question and not just me :P