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banerjeea_98
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Antmavel
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nocilis
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MA
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Go with A.

I. x could be 4 (dividors: 1, 2, 4), 9(dividors: 1, 3, 9), 25(dividors: 1, 5, 25), 49 (dividors: 1, 7, 49), .............. all x values are squares. so sqrt (x) is a prime.

II. x could be 9 (factors: 1, 3, 3), 15 (factors:1, 3, 5), 21 (factors: 1, 3, 7) ....... etc. these x values are mixed. so, sqrt (x) could be prime or could not be prime.
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HongHu
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nocilis has great explantions. (A).
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banerjeea_98
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OA is "A", good job nocilis, do u have some of these "fun facts" listed somewhere that u can share with us. :-D
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Well
Other than 2 all prime nos are odd.
So a square of a prime no can either be 4 or an odd number.

(I) says exactly 3 factors 4 has 3 1,2 and 4. All squares of prime no have only 3 factors :- 1, the prime no. and the sq of the prime number.
So Ans is A or D

(II) is not sufficient. Since If X = 81 then it has only odd factors. But 9 is not a prime number. while 25 has only odd factors 1 5 and 25 and 5 is prime.

So not D

Ans A

Thanks,
Anirban



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