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John deposited $10,000 to open a new savings account that

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John deposited $10,000 to open a new savings account that  [#permalink]

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New post 16 Jul 2012, 04:36
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John deposited $10,000 to open a new savings account that earned 4 percent annual interest, compounded quarterly. If there were no other transactions in the account, what was the amount of money in John's account 6 months after the account was opened?

(A) $10,100
(8) $10,101
(e) $10,200
(D) $10,201
(E) $10,400

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John deposited $10,000 to open a new savings account that  [#permalink]

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New post 20 Jul 2012, 03:03
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SOLUTION

John deposited $10,000 to open a new savings account that earned 4 percent annual interest, compounded quarterly. If there were no other transactions in the account, what was the amount of money in John's account 6 months after the account was opened?

(A) $10,100
(8) $10,101
(e) $10,200
(D) $10,201
(E) $10,400

Approach #1:
4 percent annual interest compounded quarterly --> 1% in 3 moths.

For the first 3 moths interest was 1% of $10,000, so $100;
For the next 3 moths interest was 1% of $10,000, plus 1% earned on previous interest of $100, so $100+$1=$101;

Total interest for 6 months was $100+$101=$201, hence balance after 6 months was $10,000+ $201=$10,201.

Answer: D.

Approach #2:
If the interest were compounded every 6 moths instead of every 3 months (quarterly) then in 6 months the interest would be 4%/2=2% of $10,000, so $200. Now, since the interest is compounded quarterly then there would be interest earned on interest (very small amount) thus the actual interest should be a little bit more than $200, only answer choice D fits.

Answer: D.

Hope it's clear.
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Re: John deposited $10,000 to open a new savings account that  [#permalink]

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New post 16 Jul 2012, 11:16
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john amount is compounded quarterly so the formula is A=P*(1+R/100)^N her p=principle R=rate of interest N=no of terms
rate of interest is 4% for a yr
so for quarter R=4/4=1%
john receive amt after 6 mnts so there are two quarter
so N=2
Amount A=P(1+R/100)^2
=10000(1+1/100)^2
=10000(1+0.01)^2
=10201
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Re: John deposited $10,000 to open a new savings account that  [#permalink]

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New post 16 Jul 2012, 12:54
D.

SI = (P*R*T) / 100
SI after 1st Quarter: (10,000*4*3/12) /100 = 100
Principal for 2nd Quarter = 10,000+ 101 = 10100
SI after 2nd Quarter: (10,101*4*3/12) /100 = 101
Amount after 2nd Quarter (6 months) = 10100 +101 = 10,201
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Re: John deposited $10,000 to open a new savings account that  [#permalink]

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New post 18 Oct 2013, 12:46
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Re: John deposited $10,000 to open a new savings account that  [#permalink]

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New post 23 May 2015, 06:05
10000*1,01*1,01 = 10201
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Re: John deposited $10,000 to open a new savings account that  [#permalink]

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New post 18 Jul 2015, 17:15
I am new to the forum, starting on GMAT studying. I saw the solutions, but we are not using the calculator on test day so I do not understand thanks
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Re: John deposited $10,000 to open a new savings account that  [#permalink]

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New post 18 Jul 2015, 21:16
Amount in John's A/c after 6 months = ($10,000 * 1%) + [($10,000 * 1%) * 1%] = $10,201. Ans (D).
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Re: John deposited $10,000 to open a new savings account that  [#permalink]

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New post 27 Jan 2016, 06:10
Bunuel wrote:
Approach #1:
4 percent annual interest compounded quarterly --> 1% in 3 months.


Although this is the method they are looking for, the question is poorly worded. By explicitly saying that 4% was earned, this implies that 4% was the effective rate, and not nominal.
Would have been better to say "the account earned a nominal annual interest rate of 4%". No more confusion.
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Re: John deposited $10,000 to open a new savings account that  [#permalink]

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New post 20 Dec 2017, 12:33
Bunuel wrote:
John deposited $10,000 to open a new savings account that earned 4 percent annual interest, compounded quarterly. If there were no other transactions in the account, what was the amount of money in John's account 6 months after the account was opened?

(A) $10,100
(8) $10,101
(e) $10,200
(D) $10,201
(E) $10,400


Since the account compounds quarterly, John earns 0.4/4 = 0.1 or 1 percent interest each quarter.

After Q1, he earns 10,000 x 0.01 = 100 dollars interest, and thus he has a total of 10,000 + 100 = 10,100 dollars in the account after the first quarter or the first 3 months.

After Q2, John earns another 10,100 x 0.01 = 101 dollars interest.

So, after 6 months, the total amount of money in John’s account is 10,100 + 101 = 10,201 dollars.

Alternate Solution:

We can use the compound interest formula A = P[(1 + (r/n)]^nt, with P = 10,000, r = 0.04, n = 4, and t = 0.5. Thus, we have P = 10,000[1+(0.04/4)]^2 = 10,000(1.01)^2 = 10,201.

Answer: D
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Re: John deposited $10,000 to open a new savings account that  [#permalink]

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New post 20 Dec 2017, 12:50
Since the interest is compounded quarterly it will increase by 1% every 3 months.

Start: 10,000

After 3 months(1 quarter): 10,000+10,000(.01)=10,100

After 6 months (2 quarters): 10,100+10,100(.01)=10,100+101=10,201
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Re: John deposited $10,000 to open a new savings account that  [#permalink]

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New post 09 Jan 2018, 18:48
Hi All,

We're told that a $10,000 investment earns 4% annual interest, compounded QUARTERLY (which means that we calculate interest 4 times per year). We're asked for the total value of the investment after 6 MONTHS. This question requires that you understand the concept behind the Compound Interest Formula (and this concept is sometimes referred to as "interest on top of interest").

If we were using SIMPLE Interest, then we'd calculate just once (and the total interest would be 4% of $10,000 = $400). However, when using Compound Interest, you calculate interest more than once per year, and you have to adjust the 'math' a bit. Based on the number of calculations that you do each year, you then have to divide the interest rate by that number of terms.

Here, we calculate 4 times per year, so each interest calculation is 4%/4 = 1%.

First 3 months = $10,000(1.01) = $10,100
Second 3 months = $10,100(1.01) = $10,201

Since the prompt asks for the total after 6 months, we don't have to do any additional work.

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Re: John deposited $10,000 to open a new savings account that  [#permalink]

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New post 13 Jan 2018, 05:42
niks18 amanvermagmat Bunuel

Quote:
We can use the compound interest formula A = P[(1 + (r/n)]^nt, with P = 10,000, r = 0.04, n = 4, and t = 0.5. Thus, we have P = 10,000[1+(0.04/4)]^2 = 10,000(1.01)^2 = 10,201.


For simplification of 10,000 * \((1.01)^2\) is my below approach valid:

10,000 * \((1.01)^2\)

= 101 * 101 or \((101)^2\) or\((100+1)^2\)

Now using \((a+b)^2\) we get \(100^2 + 2 * 100 * 1 + 1^2\) ie 10,201.
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Re: John deposited $10,000 to open a new savings account that  [#permalink]

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New post 13 Jan 2018, 05:48
1
adkikani wrote:
niks18 amanvermagmat Bunuel

Quote:
We can use the compound interest formula A = P[(1 + (r/n)]^nt, with P = 10,000, r = 0.04, n = 4, and t = 0.5. Thus, we have P = 10,000[1+(0.04/4)]^2 = 10,000(1.01)^2 = 10,201.


For simplification of 10,000 * \((1.01)^2\) is my below approach valid:

10,000 * \((1.01)^2\)

= 101 * 101 or \((101)^2\) or\((100+1)^2\)

Now using \((a+b)^2\) we get \(100^2 + 2 * 100 * 1 + 1^2\) ie 10,201.

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John deposited $10,000 to open a new savings account that earned  [#permalink]

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New post 27 Jun 2018, 19:57
hindu1988 wrote:
John deposited $10,000 to open a new savings account that earned 4 percent annual interest, compounded quarterly. If there were no other transactions in the account, what was the amount of money in John’s account 6 months after the account was opened?

(A) $10,100
(B) $10,101
(C) $10,200
(D) $10,201
(E) $10,400



Compounded quarterly means rate is divided by 4 and time is increased four times..
So RATE :- 4/4=1
TIME :- 6 months = 1/2 year = 4*1/2=2
So Amount after 6 months = \(10000(1+\frac{1}{100})^2=10000*(\frac{101}{100})^2=101^2=10201\)
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