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Is positive integer x a prime number? (1) x^2 +x ≤ 10 (2) x does not

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Is positive integer x a prime number? (1) x^2 +x ≤ 10 (2) x does not [#permalink] New post   09 May 2018, 00:26
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Is positive integer x a prime number?


(1) \(x^2+x \leq 10\)

(2) x does not have odd number of factors


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C
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superbenson
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Re: Is positive integer x a prime number? (1) x^2 +x ≤ 10 (2) x does not [#permalink] New post   09 May 2018, 02:55
from (1) x2+x≤10x2+x≤10
we can get that x equals to 1 or 2

(2) x does not have odd number of factors
insufficient

combine both (1) and (2), hence the anwer is D
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amanvermagmat
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Re: Is positive integer x a prime number? (1) x^2 +x ≤ 10 (2) x does not [#permalink] New post   09 May 2018, 05:20
superbenson wrote:
from (1) x2+x≤10x2+x≤10
we can get that x equals to 1 or 2

(2) x does not have odd number of factors
insufficient

combine both (1) and (2), hence the anwer is D


Hello

Your analysis of statements is correct. But when none of the two statements is sufficient on its own and together they are sufficient, then the answer to be marked is C, not D

Posted from my mobile device
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chandra004
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Is positive integer x a prime number? (1) x^2 +x ≤ 10 (2) x does not [#permalink] New post   13 May 2018, 12:19
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i) x^2 + x <= 10; x can be 1 or 2
Insufficient
ii) 2 has even(2 here) no. of factors and 4 has 3 factors, but 6 has 4 factors. Hence we can't be sure whether the no. is prime.
Insufficient.
Combining i) and ii):-
among 1 and 2, only 2 doesn't have odd no. of factors. Hence 2 is the no. and it's prime.
Sufficient.

Hence, C is the answer.
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Re: Is positive integer x a prime number? (1) x^2 +x ≤ 10 (2) x does not [#permalink] New post   13 May 2018, 18:04
superbenson wrote:
from (1) x2+x≤10x2+x≤10
we can get that x equals to 1 or 2

(2) x does not have odd number of factors
insufficient

combine both (1) and (2), hence the anwer is D

You mean C. D says that each statement alone is sufficient. +1 on the analysis.
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Re: Is positive integer x a prime number? (1) x^2 +x ≤ 10 (2) x does not [#permalink] New post   14 May 2018, 10:08
I did not analyse the case of number 1 in depth - answer should be C.
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Re: Is positive integer x a prime number? (1) x^2 +x ≤ 10 (2) x does not [#permalink]
14 May 2018, 10:08
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