Hi,
Please someone could explain me?
S is a set of positive integers such that if integer x is a member of S, the both x^2 and x^3 are also
in S. If the the only member of S that is neither the square nor the cube of another member of S is called the source integer, is 8 in S?
1° 4 is in S and is not the source integer
2° 64 is in S and is not the source integer
thks
DATA SUFFICIENCY SET
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1) 4 is in S and not a source integer. If a number is a source integer then its square and cube should be present in S, but the number itself need not be square or cube of another number. Since 4 is not a source integer, we can interpret that 2 is also present in S. 4 is in the set since it a square of 2. If 2 is present in S, then the cube of 2 (8) should also be present. Hence (1) is sufficient.
2) 64 is in S and not a source integer. Since 64 is not a source integer, it can be in the set as a square (of 8) or as a cube (of 4). If it is present in the set as a cube of 4 (and we do not know just by (2) alone if 4 is a source number or not) we cannot say if 8 is present in S. Hence (2) alone is not sufficient.
So think the answer should be A. What is the OA?
2) 64 is in S and not a source integer. Since 64 is not a source integer, it can be in the set as a square (of 8) or as a cube (of 4). If it is present in the set as a cube of 4 (and we do not know just by (2) alone if 4 is a source number or not) we cannot say if 8 is present in S. Hence (2) alone is not sufficient.
So think the answer should be A. What is the OA?
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sT 2 IS REALLY TRICKY.asamaverick wrote:1) 4 is in S and not a source integer. If a number is a source integer then its square and cube should be present in S, but the number itself need not be square or cube of another number. Since 4 is not a source integer, we can interpret that 2 is also present in S. 4 is in the set since it a square of 2. If 2 is present in S, then the cube of 2 (8) should also be present. Hence (1) is sufficient.
2) 64 is in S and not a source integer. Since 64 is not a source integer, it can be in the set as a square (of 8) or as a cube (of 4). If it is present in the set as a cube of 4 (and we do not know just by (2) alone if 4 is a source number or not) we cannot say if 8 is present in S. Hence (2) alone is not sufficient.
So think the answer should be A. What is the OA?
AS rightly said, 64 is in the set. Now it's prescence is becox of 8 or 4 is a mystery.
Case 1 : 64 is in S. so is 8
YES
case 2: 64 is in S. So is 4.
What if 4 is Not source integer: The set will contain 2 & thereby 8/
But what if 4 is source integer 2 wont be there in set. So No 2 & No 8
In consistent. Insufficient!
Pick A
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Can u post the explanation of how St 2 is sufficient??francoisph wrote:kaplan said
1 sufficient
2 sufficient
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Statement (1): Sufficient
If 4 is in S, and it is not the source integer, then it must be the square
or cube of the source integer. Since 4 is not the cube of any positive
integer, and it is the square of 2, 2 must be in S and must be the source
integer. It follows that if 2 is the source integer, 4 is the square of 2,
and 8 is the cube of 2. So 2, 4, and 8 would be in S. Statement (1) by
itself is sufficient to answer the question.
Statement (2): Sufficient
If 64 is in S and it is not the source integer, it could represent the
square of 8 or the cube of 4. If it represents the square of 8, then 8, 64,
and 512 are in S. The number 8 would be a member of S in this case as well.
If 64 represents the cube of 4, then 4, 16, and 64 would be in S. Since 4
is the square of 2, 2 would be in S, and 8 (the cube of 2) would also be in
S.
Either statement by itself is sufficient to answer the question.
If 4 is in S, and it is not the source integer, then it must be the square
or cube of the source integer. Since 4 is not the cube of any positive
integer, and it is the square of 2, 2 must be in S and must be the source
integer. It follows that if 2 is the source integer, 4 is the square of 2,
and 8 is the cube of 2. So 2, 4, and 8 would be in S. Statement (1) by
itself is sufficient to answer the question.
Statement (2): Sufficient
If 64 is in S and it is not the source integer, it could represent the
square of 8 or the cube of 4. If it represents the square of 8, then 8, 64,
and 512 are in S. The number 8 would be a member of S in this case as well.
If 64 represents the cube of 4, then 4, 16, and 64 would be in S. Since 4
is the square of 2, 2 would be in S, and 8 (the cube of 2) would also be in
S.
Either statement by itself is sufficient to answer the question.
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