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# A group of marbles is arranged into x rows and y columns. If the numbe

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Math Expert
Joined: 02 Sep 2009
Posts: 52905
A group of marbles is arranged into x rows and y columns. If the numbe  [#permalink]

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21 Jan 2019, 00:10
00:00

Difficulty:

25% (medium)

Question Stats:

81% (01:28) correct 19% (02:02) wrong based on 38 sessions

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A group of marbles is arranged into x rows and y columns. If the number of columns is 7 times the number of rows, and there are 343 total marbles, how many rows are there?

A 7
B 14
C 49
D 62
E 74

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Director
Joined: 18 Jul 2018
Posts: 670
Location: India
Concentration: Finance, Marketing
WE: Engineering (Energy and Utilities)
Re: A group of marbles is arranged into x rows and y columns. If the numbe  [#permalink]

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21 Jan 2019, 00:23
y = 7x

Also, xy = 343
$$7x^2 = 343$$
$$x^2 = 49$$
x = +7 or -7
As x cannot be negative, x = +7
y = 49
No. of rows, x = 7.

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Veritas Prep GMAT Instructor
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Posts: 8880
Location: Pune, India
Re: A group of marbles is arranged into x rows and y columns. If the numbe  [#permalink]

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21 Jan 2019, 02:05
Bunuel wrote:
A group of marbles is arranged into x rows and y columns. If the number of columns is 7 times the number of rows, and there are 343 total marbles, how many rows are there?

A 7
B 14
C 49
D 62
E 74

Total number of marbles = No of rows * No. of columns

343 = No of rows * 7 * No of rows (Since No of columns = 7 * No of rows)

We know that 343 = 7^3 so "No of rows" must be 7.

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Karishma
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Concentration: Sustainability, Marketing
GPA: 4
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Re: A group of marbles is arranged into x rows and y columns. If the numbe  [#permalink]

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21 Jan 2019, 07:17
Bunuel wrote:
A group of marbles is arranged into x rows and y columns. If the number of columns is 7 times the number of rows, and there are 343 total marbles, how many rows are there?

A 7
B 14
C 49
D 62
E 74

xy= 343
y=7x
7x^2 = 343
x= +/-7
IMO A
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Re: A group of marbles is arranged into x rows and y columns. If the numbe   [#permalink] 21 Jan 2019, 07:17
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