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(1) \(x<\frac{8}{9}=\frac{64}{72}\). Not sufficient by itself.

(2) \(y<\frac{1}{8}=\frac{9}{72}\). Not sufficient by itself.

(1)+(2) \(x+y<\frac{64}{72}+\frac{9}{72}=\frac{73}{72}\), so \(x+y<\frac{73}{72}\) --> \(x+y\) may or may not be less than 1 (\(x+y\) could be less than 1 as well as more than 1, in the range \((1,\frac{73}{72})\)). Not sufficient.

Re: Is x+y < 1 (1) x < 8/9 (2) y < 1/8 [#permalink]

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24 Sep 2013, 06:05

Dear Bunuel, Although i understand the solution after reading it,can you please help me in understanding the line of thinking.I never thought of multiplying the bases by a common factor.What concept's understanding would prompt me to ?

Dear Bunuel, Although i understand the solution after reading it,can you please help me in understanding the line of thinking.I never thought of multiplying the bases by a common factor.What concept's understanding would prompt me to ?

Thank you

We need to compare some fractions. Easiest ways is to find the least common denominator and proceed.
_________________

Re: Is x+y < 1 (1) x < 8/9 (2) y < 1/8 [#permalink]

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24 Sep 2013, 09:19

Bunuel wrote:

fido wrote:

Dear Bunuel, Although i understand the solution after reading it,can you please help me in understanding the line of thinking.I never thought of multiplying the bases by a common factor.What concept's understanding would prompt me to ?

Thank you

We need to compare some fractions. Easiest ways is to find the least common denominator and proceed.

Re: Is x+y < 1 (1) x < 8/9 (2) y < 1/8 [#permalink]

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25 Jan 2017, 08:59

dddmba2012 wrote:

Is x+y < 1

(1) x < 8/9 (2) y < 1/8

Each statement alone doesn't convey anything. If you combine the statements, then you get x+y < 73/72. x and y can have any value which is less than 8/9 and 1/8. Eg: x:8/9.001 y: 1/8.01 Hence E.

As we don't know the value of y, this equation is not sufficient =====> (1) NOT SUFFICIENT

(2) \(y < \frac{1}{8}\)

As we don't know the value of x, this equation is not sufficient =====> (2) NOT SUFFICIENT

Combining (1) & (2)

Lets solve x first

\(x < \frac{8}{9}\)

\(x < 8 * 0.11\)

\(x < 0.88\)

Lets solve for y

\(y < \frac{1}{8}\)

\(x < 0.125\)

Adding \(x + y = 0.88 + 0.125\)

We get \(x+y = 1.005\)

As the value of \(x + y\) can take the highest value as \(1.004\)ans any value lower than that which is \(< 1\)

We can say that x can be > 1 or x can be < 1

Hence, =====> Both (1) & (2) NOT SUFFICIENT

Hence, E is the Answer _________________

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When dealing with fractions in GMAT Quant questions, it's sometimes helpful to convert from fraction-to-decimal (doing so might make the requisite math faster or easier).

We're asked if (X+Y) is less than 1. This is a YES/NO question.

1) X < 8/9

This FACT tells us that X is LESS than .88888...., but we don't know anything about Y. Fact 1 is INSUFFICIENT

2) Y < 1/8

This FACT tells us that Y is LESS than .125, but we don't know anything about X. Fact 2 is INSUFFICIENT

Combined, we know that (X+Y) must be LESS than .8888.... + .125 = 1.01388888....

IF... the sum = 1, then the answer to the question is NO. IF... the sum = 0, then the answer to the question is YES.