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cesar.rodriguez.blanco
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PS: IF the prime numbers p and t

by cesar.rodriguez.blanco Wed Aug 19, 2009 1:34 pm

I missed this question. Please help!

If the prime numbers p and t are the only prime factors of the integer m, is m a multiple of (p^2)*t?

1) m has more than 9 positive factors
2) m is a multiple of p^3 [moderator's edit]
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Re: PS: IF the prime numbers p and t

by aditinig Wed Aug 19, 2009 5:57 pm

What is this OA?
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Re: PS: IF the prime numbers p and t

by agha79 Sun Sep 06, 2009 10:31 am

Is OA for this "B"
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Re: PS: IF the prime numbers p and t

by nitin_prakash_khanna Sun Sep 06, 2009 1:51 pm

Statement 2 is wrong, it should say...

2> m is a multiple of p^3.

St 1 tells us that there are total > 9 factors for m, which is possible with even
m = (some integer N) * p * t^4.
So NOT Sufficient

St 2 tells us that
m = np^3 and we know that p & t are the prime factors of m
so its really
m = n * p^3 * t (raised to some unknown power)
So m = some int N * p^2 * t and hence Sufficient.
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Re: PS: IF the prime numbers p and t

by RonPurewal Fri Sep 25, 2009 11:50 pm

cesar.rodriguez.blanco Wrote:I missed this question. Please help!

If the prime numbers p and t are the only prime factors of the integer m, is m a multiple of (p^2)*t?

1) m has more than 9 positive factors
2) m is a multiple of p^3


we already know that m is a multiple of t, so the only real issue here is whether there are 2 copies of "p" in its prime factorization.
i.e., we already know it's a multiple of pt; all that's missing is the second "p".

(1)
this clearly could be a "yes", if m is something like (p^1000)(t^1000). therefore, the challenge lies in looking for a "no".
we can get a "no" by keeping only one "p", and just raising "t" to a huge power. for instance, m = (p)(t^1000) will have over two thousand factors.
insufficient.

(2)
if m is a multiple of p^3, then it's at least a multiple of (p^3)(t), so, sufficient.

ans = (b)
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Re: PS: IF the prime numbers p and t

by sachin.w Fri Jan 25, 2013 3:34 am

RonPurewal Wrote:
cesar.rodriguez.blanco Wrote:I missed this question. Please help!

If the prime numbers p and t are the only prime factors of the integer m, is m a multiple of (p^2)*t?

1) m has more than 9 positive factors
2) m is a multiple of p^3


we already know that m is a multiple of t, so the only real issue here is whether there are 2 copies of "p" in its prime factorization.
i.e., we already know it's a multiple of pt; all that's missing is the second "p".

(1)
this clearly could be a "yes", if m is something like (p^1000)(t^1000). therefore, the challenge lies in looking for a "no".
we can get a "no" by keeping only one "p", and just raising "t" to a huge power. for instance, m = (p)(t^1000) will have over two thousand factors.
insufficient.

(2)
if m is a multiple of p^3, then it's at least a multiple of (p^3)(t), so, sufficient.

ans = (b)


Hi Ron,
I don't quite understand how second statement is sufficient.
Please explain with a numerical example..
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Re: PS: IF the prime numbers p and t

by jlucero Fri Jan 25, 2013 5:58 pm

sachin.w Wrote:Hi Ron,
I don't quite understand how second statement is sufficient.
Please explain with a numerical example..


p is a positive prime number, so p could be 2, 3, 5, 7...
If m is a multiple of p^3, it must be divisible by 8, 27, 125, 343...

The question asks if m is divisible by p^2, so if the number is divisible by p^3, it must be divisible by p^2.

If p is 2
m is divisible by 8
so m must be divisible by 4

If p is 3
m is divisible by 27
so m must be divisible by 9

etc.
Joe Lucero
Manhattan GMAT Instructor
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Re: PS: IF the prime numbers p and t

by sachin.w Sat Jan 26, 2013 1:11 am

jlucero Wrote:
sachin.w Wrote:Hi Ron,
I don't quite understand how second statement is sufficient.
Please explain with a numerical example..


p is a positive prime number, so p could be 2, 3, 5, 7...
If m is a multiple of p^3, it must be divisible by 8, 27, 125, 343...

The question asks if m is divisible by p^2, so if the number is divisible by p^3, it must be divisible by p^2.

If p is 2
m is divisible by 8
so m must be divisible by 4

If p is 3
m is divisible by 27
so m must be divisible by 9

etc.


Thanks Joe, but we are asked if m a multiple of (p^2)*t
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Re: PS: IF the prime numbers p and t

by RonPurewal Sat Jan 26, 2013 7:06 am

sachin.w Wrote:Thanks Joe, but we are asked if m a multiple of (p^2)*t


read the thread, please. thanks.

quoting what i wrote above:
we already know that m is a multiple of t, so the only real issue here is whether there are 2 copies of "p" in its prime factorization.
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Re: PS: IF the prime numbers p and t

by sachin.w Sat Jan 26, 2013 10:53 pm

Thanks Ron,

Just to cement my understanding..

Say 'r' is also a prime factor of m..

So, will 'm' be a multiple of 'pr'.
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Re: PS: IF the prime numbers p and t

by jnelson0612 Sat Jan 26, 2013 11:03 pm

sachin.w Wrote:Thanks Ron,

Just to cement my understanding..

Say 'r' is also a prime factor of m..

So, will 'm' be a multiple of 'pr'.


Yes, if we are assuming that the original information in the question stem is still in force--that p and t are prime factors of m.
Jamie Nelson
ManhattanGMAT Instructor