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Different Operations .

by rockeyb » Fri Apr 09, 2010 10:48 am
Which of the following operations dose " * " represent addition , subtraction , multiplication , division ?

(1) (a^3/a^2 ) * a = 1 .

(2) a -1 > 0 .

Source : Kaplan.
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by reply2spg » Fri Apr 09, 2010 11:36 am
IMO C

St 1 (a^3/a^2) gives answer a ... then a * a = 1... let's say a = 0.5 then * will be addition, division or multiplication. So not suff.

St2 a - 1 > 0 means a is greater than 1, in that case we don't know what is *

combining both we know a is greater than 1, then a divided by a = 1. So '*' is division. Therefore, ans is C
rockeyb wrote:Which of the following operations dose " * " represent addition , subtraction , multiplication , division ?

(1) (a^3/a^2 ) * a = 1 .

(2) a -1 > 0 .

Source : Kaplan.
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by chrsrook » Fri Apr 09, 2010 11:57 am
IMO C.

From A- it can be multiplication or division
From B- a>1, insufficient.

Combining, the operation can only be division.

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by gmatmachoman » Fri Apr 09, 2010 12:41 pm
chrsrook wrote:IMO C.

From A- it can be multiplication or division
From B- a>1, insufficient.

Combining, the operation can only be division.

Thanks
One more for C
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by rockeyb » Fri Apr 09, 2010 7:48 pm
OA = C . Thanks for explaining guys .
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by dxgamez » Fri Apr 09, 2010 8:13 pm
Guys,

I can't see why multiplication and addition are considered for st1. I thought it's only division and addition (for x=0.5).

Pls help with some examples!
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by thephoenix » Fri Apr 09, 2010 8:15 pm
dxgamez wrote:Guys,

I can't see why multiplication and addition are considered for st1. I thought it's only division and addition (for x=0.5).

Pls help with some examples!
for x=0.5 it can be addition or division
0.5+0.5=1
0.5/0.5=1
for a=1 it can be multiplication or division
1/1=1
1*1=1
hence insufff
to make it suff we need s2
hence c
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by rockeyb » Fri Apr 09, 2010 8:18 pm
dxgamez wrote:Guys,

I can't see why multiplication and addition are considered for st1. I thought it's only division and addition (for x=0.5).

Pls help with some examples!
Statement (1) only tells you a*a =1 .

now * can be multiplication here as we dont know what 'a' stands for ? Suppose a = 1 or -1

In both the cases it satisfies (1).

1 * 1 = 1 OR -1 *-1 = 1 . So * can be multiplication .

Similarly if you consider a= 0.5 you can say * = addition also .

Hence not sufficient.
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by thephoenix » Fri Apr 09, 2010 8:26 pm
rockeyb wrote:
dxgamez wrote:Guys,

I can't see why multiplication and addition are considered for st1. I thought it's only division and addition (for x=0.5).

Pls help with some examples!
Statement (1) only tells you a*a =1 .

now * can be multiplication here as we dont know what 'a' stands for ? Suppose a = 1 or -1

In both the cases it satisfies (1).

1 * 1 = 1 OR -1 *-1 = 1 . So * can be multiplication .

Similarly if you consider a= 0.5 you can say * = addition also .

Hence not sufficient.
for the bold part it can be division also and therefore insuff.....
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