Abdulla 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 the row?

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


OA is C

sudhir3127 wrote:

Abdulla 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 the row?

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


OA is C

i think this is a gmat prep question and the OA has to be D . Please make sure and doubly chk the questions and Answers before u post, It unncessarily creates confusion and takes a lot of time .

Am I taking a risk on the GMAT question by assuming that one of the roots will always be 'practical'??

vittalgmat wrote:Yep got it .
I used one my take aways to reduce calculation and here it is.
(I am not sure if I can apply in all cases. So pls review and let me
know your feedback.)


Let the number of rows be r
stmt 1: says
r(r+1) = 72.
=> r^2 +r -72 = 0
72 is not a perfect square. So the two roots will be of opposite sign.
Dont care what it is. one of them is +ve which is what I need coz the
chairs and/or rows cannot be -ve. Therefore sufficient.
As a side note: I wonder if I can make the above conclusion.. what if the two roots are -ve something and a +ve fraction. Then both are invalid coz we cannot have fractional rows or chairs.
Am I taking a risk on the GMAT question by assuming that one of the roots will always be 'practical'??

Some one pls comment.

Abdulla wrote:

sudhir3127 wrote:

Abdulla 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 the row?

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


OA is C

i think this is a gmat prep question and the OA has to be D . Please make sure and doubly chk the questions and Answers before u post, It unncessarily creates confusion and takes a lot of time .

In a way its FUN

One will not prove to get to the OA rather prove it to be right

Vishu
I'm so sorry.. it was my mistake .. i didn't mean it.