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In a certain conference room each row of chairs has the same number of

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In a certain conference room each row of chairs has the same number of [#permalink]

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New post 23 Sep 2010, 16:22
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A
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C
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Question Stats:

80% (00:57) correct 20% (01:35) wrong based on 15 sessions

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In a certain conference room each row of chairs has the same number of chairs, and the number of rows is 1 less than the number of chairs in a row. How many chairs are in a row?

(1) There is a total of 72 chairs
(2) After 1 chair is removed from the last row, there is a total of 17 chairs in the last 2 rows

OPEN DISCUSSION OF THIS QUESTION IS HERE: http://gmatclub.com/forum/in-a-certain- ... 29389.html
[Reveal] Spoiler: OA

Kudos [?]: 593 [0], given: 2

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Re: In a certain conference room each row of chairs has the same number of [#permalink]

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New post 23 Sep 2010, 16:48
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First, the question should have had "rows" and not "rooms", if "rooms" then answer is straight E.

so basically it is saying that there are N chairs in a row and that there are N-1 rows.

1) N (N-1) = 72. Only one way N=9
2) Remove 1 chair from the last row, you have N + N-1 chairs, that is 2N-1=17, N=9

So D
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Re: In a certain conference room each row of chairs has the same number of [#permalink]

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New post 23 Sep 2010, 16:52
TomB wrote:
In a certain conference room, each row of chairs has the same number of chairs, and the number of [highlight]rows[/highlight]is 1 less than the number of chairs in a row. How many chairs are in a row?

1) There is total of 72 chairs
2) after 1 chair removed from the last row, there are total of 17 chairs in the last 2 rows.

I didnot understand the question. please explain.


There is an error in the question.

Known: The number of chairs = no. of rows * (no. of chairs in a row)

Given the no. of rows = (no. of chairs in a row -1)

Statement 1: 72 = no. of rows * (no. of chairs in a row)

72 = (no. of rows) * (no. of rows + 1)

72 = (8*9) . Hence the number of chairs in a row is 9. Sufficient.

Statement 2: Given (2 * no. of chairs in a row) -1 = 17. Num of chairs = 9. Sufficient.

Hence answer is D.
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Re: In a certain conference room each row of chairs has the same number of [#permalink]

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New post 14 Aug 2017, 10:02
TomB wrote:
In a certain conference room each row of chairs has the same number of chairs, and the number of rows is 1 less than the number of chairs in a row. How many chairs are in a row?

(1) There is a total of 72 chairs
(2) After 1 chair is removed from the last row, there is a total of 17 chairs in the last 2 rows

OPEN DISCUSSION OF THIS QUESTION IS HERE: http://gmatclub.com/forum/in-a-certain- ... 29389.html


In a certain conference room each row of chairs has the same number of chairs, and the number of rows is 1 less than the number of chairs in a row. How many chairs are in a row?

Say # of rows is R and # of chairs per row is C.
Given: R=C-1. Question: C=?

(1) There is a total of 72 chairs --> CR=72 --> C(C-1)=72 --> C=9. Sufficient.

(2) After 1 chair is removed from the last row, there is a total of 17 chairs in the last 2 rows --> C+(C-1)=17 --> C=9. Sufficient.

Answer: D.

OPEN DISCUSSION OF THIS QUESTION IS HERE: http://gmatclub.com/forum/in-a-certain- ... 29389.html
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Re: In a certain conference room each row of chairs has the same number of   [#permalink] 14 Aug 2017, 10:02
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