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If the sum of the three different numbers is 54, what is the

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If the sum of the three different numbers is 54, what is the  [#permalink]

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New post 15 Jan 2012, 22:50
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If the sum of the three different numbers is 54, what is the largest number?

(1) The largest number is twice the smallest number.
(2) The sum of the two smaller numbers is 30.

Here, the answer is B (statement 2 alone). I don't see why statement 1 is insufficient. If the largest number is twice the smallest number, doesn't that lead only to 12 and 24 for those two numbers and 18 for the middle number?
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Re: If the sum of the three different numbers is 54, what is the  [#permalink]

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New post 15 Jan 2012, 23:13
1)
2x + y + x = 54
3x + y = 54

2x = 24
y = 18
x = 12

2x = 22
y = 21
x = 11

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Re: If the sum of the three different numbers is 54, what is the  [#permalink]

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New post 16 Jan 2012, 02:38
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1
vandygrad11 wrote:
If the sum of the three different numbers is 54, what is the largest number?

(1) The largest number is twice the smallest number.
(2) The sum of the two smaller numbers is 30.[/textarea]

Here, the answer is B (statement 2 alone). I don't see why statement 1 is insufficient. If the largest number is twice the smallest number, doesn't that lead only to 12 and 24 for those two numbers and 18 for the middle number?


If the sum of the three different numbers is 54, what is the largest number?

Given: \(x<y<z\) and \(x+y+z=54\).
Question: \(z=?\)

(1) The largest number is twice the smallest number --> \(x+y+2x=54\) --> \(3x+y=54\). Now we should find \(x\) so that \(x<y\) and \(3x+y=54\):
\(x=11\), \(y=21\), \(z=22\);
\(x=12\), \(y=18\), \(z=24\);
\(x=13\), \(y=15\), \(z=26\);

Also notice that we are not told that unknowns represent integers only so non-integer values are also valid. For example: \(x=12.5\), \(y=16.5\), and \(z=25\).
Not sufficient.

(2) The sum of the two smaller numbers is 30 --> x+y=30 --> \(30+z=54\) --> z=24. Sufficient.

Answer: B.
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Re: If the sum of the three different numbers is 54, what is the  [#permalink]

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New post 22 May 2013, 02:40
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Re: If the sum of the three different numbers is 54, what is the  [#permalink]

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New post 23 Dec 2015, 14:39
Bunuel wrote:
vandygrad11 wrote:
If the sum of the three different numbers is 54, what is the largest number?

(1) The largest number is twice the smallest number.
(2) The sum of the two smaller numbers is 30.[/textarea]

Here, the answer is B (statement 2 alone). I don't see why statement 1 is insufficient. If the largest number is twice the smallest number, doesn't that lead only to 12 and 24 for those two numbers and 18 for the middle number?


If the sum of the three different numbers is 54, what is the largest number?

Given: \(x<y<z\) and \(x+y+z=54\).
Question: \(z=?\)

(1) The largest number is twice the smallest number --> \(x+y+2x=54\) --> \(3x+y=54\). Now we should find \(x\) so that \(x<y\) and \(3x+y=54\):
\(x=11\), \(y=21\), \(z=22\);
\(x=12\), \(y=18\), \(z=24\);
\(x=13\), \(y=15\), \(z=26\);

Also notice that we are not told that unknowns represent integers only so non-integer values are also valid. For example: \(x=12.5\), \(y=16.5\), and \(z=25\).
Not sufficient.

(2) The sum of the two smaller numbers is 30 --> x+y=30 --> \(30+z=54\) --> z=24. Sufficient.

Answer: B.

How do we know z is largest
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Re: If the sum of the three different numbers is 54, what is the  [#permalink]

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New post 23 Dec 2015, 17:29
sagnik242 wrote:
Bunuel wrote:
vandygrad11 wrote:
If the sum of the three different numbers is 54, what is the largest number?

(1) The largest number is twice the smallest number.
(2) The sum of the two smaller numbers is 30.[/textarea]

Here, the answer is B (statement 2 alone). I don't see why statement 1 is insufficient. If the largest number is twice the smallest number, doesn't that lead only to 12 and 24 for those two numbers and 18 for the middle number?


If the sum of the three different numbers is 54, what is the largest number?

Given: \(x<y<z\) and \(x+y+z=54\).
Question: \(z=?\)

(1) The largest number is twice the smallest number --> \(x+y+2x=54\) --> \(3x+y=54\). Now we should find \(x\) so that \(x<y\) and \(3x+y=54\):
\(x=11\), \(y=21\), \(z=22\);
\(x=12\), \(y=18\), \(z=24\);
\(x=13\), \(y=15\), \(z=26\);

Also notice that we are not told that unknowns represent integers only so non-integer values are also valid. For example: \(x=12.5\), \(y=16.5\), and \(z=25\).
Not sufficient.

(2) The sum of the two smaller numbers is 30 --> x+y=30 --> \(30+z=54\) --> z=24. Sufficient.

Answer: B.

How do we know z is largest


Hi,

the statement tells us that 30 is the sum of two smallest numbers..
so the remaining difference will have to be the third number, which will be the largest
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1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


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If the sum of the three different numbers is 54, what is the  [#permalink]

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New post 17 Feb 2016, 18:12
Bunuel wrote:
vandygrad11 wrote:
If the sum of the three different numbers is 54, what is the largest number?

(1) The largest number is twice the smallest number.
(2) The sum of the two smaller numbers is 30.[/textarea]

Here, the answer is B (statement 2 alone). I don't see why statement 1 is insufficient. If the largest number is twice the smallest number, doesn't that lead only to 12 and 24 for those two numbers and 18 for the middle number?


If the sum of the three different numbers is 54, what is the largest number?

Given: \(x<y<z\) and \(x+y+z=54\).
Question: \(z=?\)

(1) The largest number is twice the smallest number --> \(x+y+2x=54\) --> \(3x+y=54\). Now we should find \(x\) so that \(x<y\) and \(3x+y=54\):
\(x=11\), \(y=21\), \(z=22\);
\(x=12\), \(y=18\), \(z=24\);
\(x=13\), \(y=15\), \(z=26\);

Also notice that we are not told that unknowns represent integers only so non-integer values are also valid. For example: \(x=12.5\), \(y=16.5\), and \(z=25\).
Not sufficient.

(2) The sum of the two smaller numbers is 30 --> x+y=30 --> \(30+z=54\) --> z=24. Sufficient.

Answer: B.



From Statement 2 how do we know that x is not 29 and y=1, or x=28 and y=2?
In those cases x would be the largest number.
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Re: If the sum of the three different numbers is 54, what is the  [#permalink]

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New post 17 Feb 2016, 18:23
3
FasuSek wrote:
Bunuel wrote:
vandygrad11 wrote:
If the sum of the three different numbers is 54, what is the largest number?

(1) The largest number is twice the smallest number.
(2) The sum of the two smaller numbers is 30.[/textarea]

Here, the answer is B (statement 2 alone). I don't see why statement 1 is insufficient. If the largest number is twice the smallest number, doesn't that lead only to 12 and 24 for those two numbers and 18 for the middle number?


If the sum of the three different numbers is 54, what is the largest number?

Given: \(x<y<z\) and \(x+y+z=54\).
Question: \(z=?\)

(1) The largest number is twice the smallest number --> \(x+y+2x=54\) --> \(3x+y=54\). Now we should find \(x\) so that \(x<y\) and \(3x+y=54\):
\(x=11\), \(y=21\), \(z=22\);
\(x=12\), \(y=18\), \(z=24\);
\(x=13\), \(y=15\), \(z=26\);

Also notice that we are not told that unknowns represent integers only so non-integer values are also valid. For example: \(x=12.5\), \(y=16.5\), and \(z=25\).
Not sufficient.

(2) The sum of the two smaller numbers is 30 --> x+y=30 --> \(30+z=54\) --> z=24. Sufficient.

Answer: B.



From Statement 2 how do we know that x is not 29 and y=1, or x=28 and y=2?
In those cases x would be the largest number.


Hi,
the answer lies within the statement 2 itself..
(2) The sum of the two smaller numbers is 30

now this tells us that 30 is the sum of two smaller numbers..
so x cannot be 28 or 29 it has to be less than the largest number 54-30=24..

hope it helps
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1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


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Re: If the sum of the three different numbers is 54, what is the  [#permalink]

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New post 26 Jan 2017, 21:17
When you modify the original condition and the question, based on a<b<c, you only need to know a+b
from 1) a+b+c=54, c=54-(a+b).
Since 2) a+b=30, c=54-30=24,
which is unique and sufficient.
Therefore the answer is B.
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Re: If the sum of the three different numbers is 54, what is the  [#permalink]

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New post 02 Nov 2018, 15:16
geometric wrote:
If the sum of the three different numbers is 54, what is the largest number?

(1) The largest number is twice the smallest number.
(2) The sum of the two smaller numbers is 30.

\(\left\{ \matrix{
a > b > c \hfill \cr
a + b + c = 54\,\,\,\,\,\, \hfill \cr} \right.\,\,\,\,;\,\,\,\,\,\,\,\,\,\,?\,\, = \,\,a\)

Let´s start with statement (2) not only because it´s easier, but also because it will help us finding (uniqueness or) a BIFURCATION of the other statement!

\(\left( 2 \right)\,\,\,b + c = 30\,\,\,\,\, \Rightarrow \,\,\,\,\,? = a = 54 - 30 = 24\,\,\,\,\,\, \Rightarrow \,\,\,\,\,\,{\rm{SUFF}}.\)

\(\left( 1 \right)\,\,a = 2c\,\,\,\,\left\{ \matrix{
\,{\rm{Take}}\,\,\left( {a,b,c} \right) = \left( {24,18,12} \right)\,\,\,\,\, \Rightarrow \,\,\,\,a = 24\,\, \hfill \cr
\,{\rm{Take}}\,\,\left( {a,b,c} \right) = \left( {26,15,13} \right)\,\,\,\,\, \Rightarrow \,\,\,\,a = 26\,\, \hfill \cr} \right.\,\,\,\,\,\, \Rightarrow \,\,\,\,\,\,{\rm{INSUFF}}{\rm{.}}\)


This solution follows the notations and rationale taught in the GMATH method.

Regards,
Fabio.
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