If x and y are positive integer then xy is a multiple of 8?
A)Least common divisor is 10.
B)Greatest common multiple is 100.
Please help me i really got confused......
LCD and GCM
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A) x=y=10,not
x=2,y=5, not
sufficient
B) x=y=100, yes. thus sufficient
IMO D
x=2,y=5, not
sufficient
B) x=y=100, yes. thus sufficient
IMO D
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Just remember;
Product of 2 Nos = [LCM of the 2 Nos] * [HCF of the 2 Nos]
(1) & (2) gives you both individually but you need both.
So, C IMO
Product of 2 Nos = [LCM of the 2 Nos] * [HCF of the 2 Nos]
(1) & (2) gives you both individually but you need both.
So, C IMO
NehaPathak wrote:If x and y are positive integer then xy is a multiple of 8?
A)Least common divisor is 10.
B)Greatest common multiple is 100.
Please help me i really got confused......
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A few problems with the wording here. Least common divisor? Greatest common multiple?NehaPathak wrote:If x and y are positive integer then xy is a multiple of 8?
A)Least common divisor is 10.
B)Greatest common multiple is 100.
Please help me i really got confused......
I'm assuming that the question should read:
If x and y are positive integers, is xy a multiple of 8?
1)The greatest common divisor of x and y is 10
2)The least common multiple of x and y is 100
Let's find contradictory values for x and y to show that each statement alone is not sufficient.
Statement 1:
Consider 2 different cases that satisfy the condition that the greatest common divisor of x and y is 10
case a: x=10 and y=10, in which case xy is not a multiple of 8
case b: x=10 and y=100, in which case xy is a multiple of 8
Statement 1 is not sufficient
Statement 2:
Consider 2 different cases that satisfy the condition that the least common multiple of x and y is 100
case a: x=4 and y=25, in which case xy is not a multiple of 8
case b: x=10 and y=100, in which case xy is a multiple of 8
Statement 2 is not sufficient
Statements 1 & 2:
We have a nice rule that says "[GCD of x and y][LCM of x and y] = xy"
So, from statements 1 and 2, we know that "[10][100] = xy"
So, xy = 1000 and 1000 is a multiple of 8
Since we can now answer the target question with certainty, we can see that the answer is C.
Cheers,
Brent
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