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Bunuel
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If x and y are integers, what is the value of x? 08 Dec 2016, 14:00
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E
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Difficulty:

25% (medium)

Question Stats:

79% (01:15) correct 21% (00:43) wrong based on 40 sessions

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If x and y are integers, what is the value of x?

(1) The least common multiple of x and y is 840.
(2) The greatest common factor of x and y is 28.
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E
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If x and y are integers, what is the value of x? 08 Dec 2016, 21:03
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Bunuel
If x and y are integers, what is the value of x?

(1) The least common multiple of x and y is 840.
(2) The greatest common factor of x and y is 28.


(1) X could be 28 or 840...not suff..
(2) x =28 & y=840
if x=840 & y=28------not suff

Combining both again as in (2)
Not suff

Ans E
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RR88
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If x and y are integers, what is the value of x? 09 Dec 2016, 01:36
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Option E)

X = ?

S1.
LCM(X,Y) = 840
: (X,Y) = (3,280); (280,3); (7, 120); (120,7) . . .
No unique solution

Insufficient

S2
HCF(X,Y) = 28
: (X,Y) = (28,840); (840,28)...
No unique solution

Insufficient

S1 + S2
LCM(X,Y) = 840 & HCF(X,Y) = 28
: (X,Y) = (28,840); (840,28)
No unique solution

Insufficient
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If x and y are integers, what is the value of x? 12 Dec 2016, 04:47
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To find: value of x

Statement 1: LCM(x,y)= 840
LCM(x,y)= 2^3. 3^1. 5^1. 7^1
We know LCM takes the highest value of the prime factors but we have no clue about the values of x and y. Thus insufficient.

BCE

Statement 2: HCF(x,y)= 28
HCF(x,y)= 2^2. 7^1

HCF takes the common factors and their lowest powers.
x can be 2^0 or 2^1 or 2^2 and 7^0 or 7^1
Same goes for y.

Hence we don't know the exact values of both x and y.

Insufficient.

Taking both the statements together.
HCF(x,y). LCM(x,y)= x.y
Again we do not know the value of y in order to find the value of x.

Therefore the correct choice according to me is E.
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Bunuel
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