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Is a > b ?

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Intern
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Joined: 16 Jun 2010
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Is a > b ?  [#permalink]

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New post Updated on: 03 Sep 2015, 02:11
12
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

60% (01:29) correct 40% (01:12) wrong based on 425 sessions

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Is a > b ?

(1) a/b = 7/10

(2) a = 70/100*b

Originally posted by Maude on 25 Aug 2010, 02:11.
Last edited by Bunuel on 03 Sep 2015, 02:11, edited 1 time in total.
Renamed the topic and edited the question.
Manager
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Re: Is a > b ?  [#permalink]

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New post 25 Aug 2010, 03:41
1
This type of problem is probably solved fastest by picking numbers. The key is to think about positive and negative numbers.

Statement 1:

Cross-multiply to obtain 10*a = 7*b

This will hold true e.g. if a = 7 and b = 10 => a < b, but also if a= -7 and b = -10 => a > b. Hence, statement A is not sufficient.

Statement 2:

I assume the statement reads a = (70 / 100)*b, otherwise it would contradict the first statement. Again cross-multiple and simplify the fraction to obtain 10*a = 7*b.

The second statement doesn't provide you with any additional information. Thus, E is the solution to this problem.
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Re: Is a > b ?  [#permalink]

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New post 25 Aug 2010, 03:42
1
both statements essentially say the same thing.. ratio: a:b=7:10 => 10a=7b;

now just plug in some values to see if you can get any definitive answers:

assume a=7, b=10 or a=14, b=20 and so on.... (a< b)

but there are negative answers as well.... a=-7, b=-10 => a > b

I would go with E.....
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Re: Is a > b ?  [#permalink]

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New post 03 Sep 2015, 02:15
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Is a > b ?  [#permalink]

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New post 04 Sep 2015, 04:45
Forget conventional ways of solving math questions. In DS, Variable approach is

the easiest and quickest way to find the answer without actually solving the

problem. Remember equal number of variables and equations ensures a solution.


Is a > b ?

(1) a/b = 7/10

(2) a = 70/100*b
==> transforming the original condition and the question using variable approach method, we have 2 variables (a,b) and in order to match the number of variables and equations we need 2 equations. Since there is 1 each in 1) and 2), C is likely the answer.

Using both 1) & 2) together, the answer is yes if a=-7, b=10, while the answer is no if a=7, b=10. Since the conditions and not suffiicent. the answer is E
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Re: Is a > b ?  [#permalink]

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New post 10 Jul 2018, 10:29
(1) a/b = 7/10

Given only ratio
If multiplied term is negative then a>b
but if multiplied term is positive then b>a

Multiple cases so insufficient

(2) a = 70/100*b

rearranging gives statement 1 only
so insufficient

E is answer

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Re: Is a > b ?  [#permalink]

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New post 10 Sep 2018, 01:47
Maude wrote:
Is a > b ?

(1) a/b = 7/10

(2) a = 70/100*b


Is \(a>b \quad?\)

(1) \(\frac{a}{b} = \frac{7}{10}\)

Taking \(a = 7\) and \(b = 10,\quad \frac{a}{b}=\frac{7}{10}\)

Is \(a>b ? : No\) ; as \(7<10\).

Taking \(a = - 7\) and \(b = -10,\quad \frac{a}{b} = \frac{-7}{-10}=\frac{7}{10}\)

Is \(a>b ? : Yes\) ; as \(-7>-10\).

Statement \(1\) alone is not sufficient.

(2) \(a = \frac{70}{100}*b\)

\(a = \frac{70}{100}*b\) can be reduced to \(a = \frac{7}{10} *b\)

Taking \(a = 7\) and \(b = 10,\quad a=\frac{7}{10}*b\)

Is \(a>b ? : No\) ; as \(7<10\).

Taking \(a = - 7\) and \(b = -10,\quad a = \frac{7}{10}b\)

Is \(a>b ? : Yes\) ; as \(-7>-10\)

Statement \(2\) alone is not sufficient.

As Statement (1) and statement (2) are the same with only exception that in statement 1, b cannot be zero while statement 2, b can be 0.
Combining both will also be insufficient to answer: Is a > b ?
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Re: Is a > b ?   [#permalink] 10 Sep 2018, 01:47
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