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# If x, y and z are distinct prime numbers..

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Joined: 03 Sep 2012
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Kudos [?]: 136 [1] , given: 31

If x, y and z are distinct prime numbers.. [#permalink]  21 Nov 2012, 08:07
1
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Difficulty:

35% (medium)

Question Stats:

64% (01:47) correct 36% (01:10) wrong based on 92 sessions
If x, y and z are distinct prime numbers, how many positive factors does (xy)^z have?

(1) z=5

(2) x+y = 10
[Reveal] Spoiler: OA

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Kudos [?]: 43 [0], given: 8

Re: If x, y and z are distinct prime numbers.. [#permalink]  21 Nov 2012, 08:19
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A for me

Given that x,y and z are three distinct prime numbers
frm statement 1) z=5

so (xy)^5 = (x^5)*(y^5)
and so the no of positive factors is (5+1)*(5+1)=6*6=36

frm statement 2) x+y = 10
which means the possible combination is 3,7 or 7,3
if z=1 we have 4 factors
if z=2 we will have 9 factors and so on

so 2 is insufficient
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KPV

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Re: If x, y and z are distinct prime numbers.. [#permalink]  22 Nov 2012, 05:08
Expert's post
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If x, y and z are distinct prime numbers, how many positive factors does (xy)^z have?

$$(xy)^z=x^z*y^z$$. Now, since x and y are distinct prime numbers, then the number of factors equal to (z+1)(z+1) (check here: math-number-theory-88376.html). Thus, all we need to know to answer the question is the value of z.

(1) z=5. Sufficient.

(2) x+y = 10. Not sufficient.

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Kudos [?]: 137 [0], given: 82

Re: If x, y and z are distinct prime numbers.. [#permalink]  24 Nov 2012, 07:14
nice question !!

its A..

(z+1) (z+1)
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Re: If x, y and z are distinct prime numbers.. [#permalink]  21 Oct 2014, 15:22
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: If x, y and z are distinct prime numbers..   [#permalink] 21 Oct 2014, 15:22
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