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# For a certain savings account, the table shows the three

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MBA Section Director
Joined: 19 Mar 2012
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Location: India
GMAT 1: 760 Q50 V42
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WE: Marketing (Non-Profit and Government)
Re: For a certain savings account, the table shows the three [#permalink]

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29 Mar 2013, 09:44
debayan222 wrote:
[
Hey Guys,
I'm sorry but I'm not getting it..
In bank account, if I deposit \$1000.00 on say Jan-01 and if for next 30 days there is no transaction then at the end 30 days my bank account will have \$ 30000.00 as per your explanations.Does that make sense guys ?Keeping money idle in the bank and its getting multiplied with no. of days kept in the account...I mean certainly there will be addition of Interest but that will not fetch you 30 times your deposit in 30 days.

Then, why we're considering this theory..Bunuel I would request you help.

Please come up with a deep analysis on this.

Its NOT about cash inflow. ITS BECAUSE THE PROMPT MENTIONS THE AVERAGE OF BALANCES
For example
If I have a balance of \$1000 for 3 days in my a/c the average is
\$(1000X3)/3 = 1000

If I had withdrawn \$500 on the second day BY THE LOGIC OF THE PROMPT THE AVERAGE WILL BE
\$(1000+500+500)/3 = \$667

Hope its clear
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Re: For a certain savings account, the table shows the three [#permalink]

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29 Mar 2013, 16:59
Since there is only three things happening on the account...

\$1000 to start off with, -\$350 (\$750 left), -\$500 (\$250 left) how much do we need to deposit to take the avg back to \$1000?

1000+750+250 = 2000, divide this by 3 (2000/3) and we get roughly 666. Then \$1000 - \$666 = \$444, so the account must go up to \$1000 + 444 =1444 (since 666 is roughly) its 1450 that was deposited on that day.
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Re: For a certain savings account, the table shows the three [#permalink]

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14 Jan 2015, 07:54
I had the same doubt as liarish

Thank You Bunuel The explanation was crisp.

Kudos [?]: 211 [0], given: 79

Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
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Location: Pune, India
Re: For a certain savings account, the table shows the three [#permalink]

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27 Sep 2016, 00:14
anon1 wrote:
Attachment:
Untitled.png
For a certain savings account, the table shows the three transactions for the month of June. The daily balance for the account was recorded at the end of each of the 30 days in June. If the daily balance was \$1,000 on June 1 and if the average (arithmetic mean) of the daily balances for June was \$1,000, what was the amount of the deposit on June 21?

A. \$1,000
B. \$1,150
C. \$1,200
D. \$1,450
E. \$1,600

[Reveal] Spoiler:
Okay, so june 1 - june 10, the sum of the daily balance in this time period here is 10,000 (because initial balance is 1000, and nothing changes)
june 11-15 - the sum here is 3250 (1000-350)*5
june 15-20 the sum here is 750 (1000-350-500)*5

the sum of all those is 14,000.

Since we want to find a deposit, whose sum makes the total sum of all the balances 30,000 / 30 = 1,000

I did 30,000 - 14,000 which gives me 16,000.

so the sum of the balances for rest of the days (10) must equal 16,000. I do 16,000/10

and that's 1,600. E. But thats wrong. The answer is D

What am I donig wrong here? and what is the false logic?

Responding to a pm: For the ease of calculations, you can use deviation from the mean concept for weighted averages.

Shortfall = Excess
350*20 + 500*15 = 10*x
x = 1450

The concept has been discussed in detail here:
http://www.veritasprep.com/blog/2016/09 ... -averages/
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Re: For a certain savings account, the table shows the three [#permalink]

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12 Oct 2017, 03:32
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Re: For a certain savings account, the table shows the three   [#permalink] 12 Oct 2017, 03:32

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