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m01 - Q 20

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m01 - Q 20 [#permalink] New post 18 Sep 2008, 02:19
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Question Stats:

82% (01:32) correct 18% (00:46) wrong based on 418 sessions
If Jim saved a total of $90 in 3 weeks, how much did he save in week 2?

(1) Jim's average savings for the first 2 weeks were $20
(2) Jim's first week's savings were half of his savings in week 2 and a third of his savings in week 3

[Reveal] Spoiler: OA
B

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Answer explaination :

Let's suppose , S1 , S2 and S3 are the amounts Jim saved for the first, second, and third week correspondingly.

From statement (1) we have that S1 + S2 = 120, but the question says that S1 + S2 + S3 = 180, so S3 = -40; he lost $40 during the third week.

From the statement (2) we can construct system of equations:
S1 + S2 + S3 = 80
2S1 - S2 = 0
3S1 - S3 = 0

How was above two equations written using the statement ?Subtracting second equation from the third gives us

Solving it gives the value of .

The answer is B.
[Reveal] Spoiler: OA
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Re: m01 - Q 20 explaination not clear pls put some light [#permalink] New post 19 Sep 2008, 03:09
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Frm (2) let the savings for three weeks be x, 2x, 3x
Then x+2x+3x= total savings=80
x can be found hence saving for second week can also be found
Ans: B
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Re: m01 - Q 20 explaination not clear pls put some light [#permalink] New post 21 Sep 2008, 09:35
I believe the first statement is meaningles. IMO saving must be positive whereas just like he mentioned it comes out to be negative ? Should be corrected.
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Re: m01 - Q 20 explaination not clear pls put some light [#permalink] New post 18 Oct 2008, 13:40
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The answer and explanation are correct, I solved it via S2, same as ritula, sum of the parts, x = 13 1/3, 2x = 26 2/3.

But S1 then contradicts S2. As I understand it, that's not supposed to be possible on a DS question. S1 can be insufficient, but it can't be wrong. In this case it's wrong.

If S1 stated that the average for the first 2 weeks was $20, this would be reconciled (and the answer stays the same).
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Re: m01 - Q 20 explaination not clear pls put some light [#permalink] New post 23 Oct 2008, 05:51
Thanks, we'll edit the question. It indeed has a typo.
+1

scorcho wrote:
The answer and explanation are correct, I solved it via S2, same as ritula, sum of the parts, x = 13 1/3, 2x = 26 2/3.

But S1 then contradicts S2. As I understand it, that's not supposed to be possible on a DS question. S1 can be insufficient, but it can't be wrong. In this case it's wrong.

If S1 stated that the average for the first 2 weeks was $20, this would be reconciled (and the answer stays the same).

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Re: m01 - Q 20 explaination not clear pls put some light [#permalink] New post 31 Oct 2008, 06:25
OK. may be I misinterpreted statement 2.

I concluded

S1 = 1/2 S2 + 1/3 S3 so I chose answer 5.

But in the answer explanation,

2S1 - S2 =0
3S1 - S3 = 0

In Statement 2, it used 'And' not 'Or' right? can you guys explain me understanding this?

Thanks.
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Re: m01 - Q 20 explaination not clear pls put some light [#permalink] New post 31 Oct 2008, 08:36
dzyubam wrote:
Thanks, we'll edit the question. It indeed has a typo.
+1

scorcho wrote:
The answer and explanation are correct, I solved it via S2, same as ritula, sum of the parts, x = 13 1/3, 2x = 26 2/3.

But S1 then contradicts S2. As I understand it, that's not supposed to be possible on a DS question. S1 can be insufficient, but it can't be wrong. In this case it's wrong.

If S1 stated that the average for the first 2 weeks was $20, this would be reconciled (and the answer stays the same).


Yeah, thats necessary to make the question worthful.

Thanks.
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Re: m01 - Q 20 explaination not clear pls put some light [#permalink] New post 31 Oct 2008, 09:45
GMATTIGER,

can you explain a bit more? are you saying that is correct(usning 'and' in statement 2 instead of an 'or') or wrong?

any help would be appreciated.

Thanks.
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Re: m01 - Q 20 explaination not clear pls put some light [#permalink] New post 01 Nov 2008, 11:14
ugimba wrote:
GMATTIGER, can you explain a bit more? are you saying that is correct(usning 'and' in statement 2 instead of an 'or') or wrong? any help would be appreciated.
Thanks.


According to the question:

From statement 1: (w1 + w2)/2 = 60
w1 + w2 = 120

Since the question says that saving in 3 weeks is 80, how is it possible to 120 savings in 2 weeks. Ok, The question might assume that there is a negative savings of $40 in w3. Ok agreed.

From statement 2: w1 = w2/2 = w3/3
so w2 = 2w1 and w3 = 3w1
w1 + w2 + w3 = 80

Since w1+w2+w3 = 80, and w1+w2 = 120, it cannot be true that w3 = 3w1 because w3 saving is -ve and w1 is +ve.. Therefore the assumptions are self contradictory. However, I am sure "dzyubam" might have already changed the question as required.



Quote:
Jim has saved $80 in 3 weeks. How much did he save in Week 2?

1. Average savings for the first 2 weeks are $60
2. First week savings are half of what he saved in week 2 and a third of what he saved in week 3

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Re: M1 - 22 [#permalink] New post 05 Feb 2009, 21:56
the next # after 324,700 to have tens digit 2 and units digit 1 is 324721, the one after that is: 324821, 324921, etc. So we see here that # w/tens digit 2 and units digit 1 comes every 100 #s.
So to get the answer, we find out how many 100 #s are there btw 458,600 and 324,700:
(458,600-324,700)/100=1338, 1338+1=1339 to be inclusive.
So the answer is A: 1339
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Re: M1 - 22 [#permalink] New post 06 Feb 2009, 11:08
wcgmatclub wrote:
the next # after 324,700 to have tens digit 2 and units digit 1 is 324721, the one after that is: 324821, 324921, etc. So we see here that # w/tens digit 2 and units digit 1 comes every 100 #s.
So to get the answer, we find out how many 100 #s are there btw 458,600 and 324,700:
(458,600-324,700)/100=1338, 1338+1=1339 to be inclusive.
So the answer is A: 1339


small correction..

](458,600-324,700)/100=1339 that's the answer.. why are you adding 1
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Re: m01 - Q 20 explaination not clear pls put some light [#permalink] New post 12 Jul 2011, 06:56
itiskavikatha wrote:
If Jim saved a total of $90 in 3 weeks, how much did he save in week 2?

1. Jim's average savings for the first 2 weeks were $20
2. Jim's first week's savings were half of his savings in week 2 and a third of his savings in week 3

[Reveal] Spoiler: OA
B

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1) offcourse is not sufficient to solve
2) S1+S2+S3 = 90
S1 = 1/2S2
S3 = 3S1 = 3/2(S2)

S2(1+1/2+3/2) = 90
S2 = 180/6 = 30 hence B
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Re: m01 - Q 20 explaination not clear pls put some light [#permalink] New post 12 Jul 2011, 11:02
Here is something I do not understand.

According to statement one, the average savings for the first two weeks were $20. I assumed that meant after two weeks he had $40.

Where are people getting $120 from?
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Re: m01 - Q 20 explaination not clear pls put some light [#permalink] New post 16 Jul 2012, 04:26
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Here's my logic to this question:

1) He could have saved $10 in week 1 and $30 in week 2 and you get an average of $20 OR he could have saved $20 in both week 1 and 2 and that gives you an average of $20. Clearly Not sufficient

2) You get only one value for this. Week 2= $30... Week 1= $15.... Week 3= $45
All 3 weeks equal $90. Try to plug in other values and it doesn't work.

Answer B
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Re: m01 - Q 20 [#permalink] New post 19 Jul 2012, 14:38
1) First statement only give the average of the first two weeks. May be there was no income in the first or second week. Incomplete information.

2) you can create a equation to solve with this information 1/2x + x + 3(1/2x) = 90 (You don't have to solve, just create an equation to establish relationship)

Ans : B ( 2nd statement is sufficient to ans., but not 1st)
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Re: m01 - Q 20 [#permalink] New post 20 Jul 2012, 04:18
Expert's post
itiskavikatha wrote:
If Jim saved a total of $90 in 3 weeks, how much did he save in week 2?

(1) Jim's average savings for the first 2 weeks were $20
(2) Jim's first week's savings were half of his savings in week 2 and a third of his savings in week 3


Note that: on the GMAT, two data sufficiency statements always provide TRUE information and these statements never contradict each other.

But for this question, from the first statement we get that the total savings for the first 2 weeks were $40 and from the second statement we get that the total savings for the first 2 weeks were $15+$30=$45, so the statements clearly contradict each other.

Revised question reads:

If Jim saved a total of $90 in 3 weeks, how much did he save in week 2?

Say S_1, S_2, and S_3 are the amounts Jim saved for the first, second, and third week, respectively.

(1) Jim's average savings for the first 2 weeks were $22.5. Given: S_1+S_2=2*22.5=45, not sufficient to get the value of S_2.

(2) Jim's first week's savings were half of his savings in week 2 and a third of his savings in week 3. Given: 2*S_1=S_2 and 3*S_1=S_3. Since, also given that S_1+S_2+S_3=90, then S_1+2*S_1+3*S_1=90, which gives S_1=15. Therefore S_2=2*S_1=30. Sufficient..

Answer: B.

Hope it's clear.
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Re: m01 - Q 20 [#permalink] New post 07 Aug 2012, 23:07
B is right guys??!!!
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Re: m01 - Q 20 [#permalink] New post 07 Aug 2012, 23:48
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Re: m01 - Q 20   [#permalink] 07 Aug 2012, 23:48
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