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Director
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N is a positive integer and N<10,000, how many prime [#permalink]
 11 Jan 2005, 14:50
N is a positive integer and N<10,000, how many prime integers does N have?
1) N is a multiple of 30.
2) N is a multiple of 70.
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VP
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I will go with 'C'
From 1: N can be 30, 60, 90, ........210............300..........
From 2: N can be 70, 140, 210.......
Both put together we know that N can be 210, 420, 630...........
Based on this we can say that N can have 4 prime integers 2, 3, 5, & 7
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Director
Joined: 07 Jun 2004
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i think the Q has a typo it means Prime factors i guess
then i will go with C too
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Director
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rthothad wrote: I will go with 'C'
From 1: N can be 30, 60, 90, ........210............300..........
From 2: N can be 70, 140, 210.......
Both put together we know that N can be 210, 420, 630...........
Based on this we can say that N can have 4 prime integers 2, 3, 5, & 7
there is not OA but I will choose E.
If 210 * 11 = 2310 < 10000 and are mutiple of 30 and 70, but have 5 prime integers.
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SVP
Joined: 25 Nov 2004
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rthothad wrote: I will go with 'C'
From 1: N can be 30, 60, 90, ........210............300..........
From 2: N can be 70, 140, 210.......
Both put together we know that N can be 210, 420, 630...........
Based on this we can say that N can have 4 prime integers 2, 3, 5, & 7
Agree with rthothad. OA is C.
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Intern
Joined: 06 Dec 2004
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hard one from real test [#permalink]
13 Jan 2005, 12:54
Can you please elaborate why you have picked C
For me E is the answer
As DLMD pointed the prime factor can be either 4 or 5
- Joe
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hard one from real test
[#permalink]
13 Jan 2005, 12:54
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