How many positive factors does positive integer N have?

Question

(1) N^2 has three positive factors
(2) 2N has four positive factors

Are You Up For the Challenge: 700 Level Questions

TarunKumar1234 · Answer

How many positive factors does positive integer N have?

(1) N^2 has three positive factors

this means N has 2 factors, therefore N is prime. And will have 2 factors. Sufficient.

(2) 2N has four positive factors

ok for ex: N = 4 then 2N will have four factors and in this case, N will have 3 factors

for ex: N = 5 then also 2N will have four factors and in this case, N will have 2 factors

Not sufficient.

IMO A

CEdward · Answer

I think the answer is A.

ST1.
N = 2 : 1, 2, 4 YES
N = 3: 1, 3, 9 YES 
In other words, if you take any of the primes and square them you will end up with three positive factors. But, of course all primes have only two factors: 1 and itself. N also has, therefore, 2 factors. 
Sufficient

ST2.
N = 4 --> 2N = 8: 1, 2,4, 8 --> So N has 3 factors
N = 5 --> 2N = 10: 1, 2, 5, 10 --> So N has 2 factors since 5 is prime
Insufficient.

callmeDP · Answer

How many positive factors does positive integer N have?

(1) N^2 has three positive factors

this means N has 2 factors, therefore N is prime. And will have 2 factors. Sufficient.

(2) 2N has four positive factors

ok for ex: N = 4 then 2N will have four factors and in this case, N will have 3 factors

for ex: N = 5 then also 2N will have four factors and in this case, N will have 2 factors

Not sufficient.

IMO A

akadiyan · Answer

How many positive factors does positive integer N have?

(1) N^2 has three positive factors
 N^2  will always have 2 factors N and  N^2  and 1 is a factor of all positive integers. From this we know that N is a prime number and hence N has 2 factors

Option 1  SUFFICIENT

(2) 2N has four positive factors
If N=4, then 2N=8 and has 4 factors , but N has 3 factors
If N=3, then 2N=6 and 6 has 4 factors, but N has only 2 factors.
we get 2 different answers

Option 2  INSUFFICIENT

Ans  A

MHIKER · Answer

(1) This means N is a prime number. Only the perfect square of a prime number has exactly three positive factors. N has two factors. Sufficient.

(2) If N=5, which has Two factors

2N=10 has;10, 5, 2, 1 four factors.

If N=4

2N=8; has; 8, 4, 2, 1 has four factors. But N=4; 4, 2, 1 Three factors.

Thus 2N may have four factors but N may have 3 or 2 factors. Insufficient.

The answer is A.

carouselambra · Answer

IMO A

How many positive factors does positive integer N have?

(1) N^2 has three positive factors
Examples: 4,9,25,49
Each value of N has two factors.
(A) is sufficient

(2) 2N has four positive factors
Example:
8(where N=4). N has 3 factors.
10(where N=5). N has 2 factors.
(B) is not sufficient.

GCMEMBER · Answer

How many positive factors does positive integer N have?

(1) N^2 has three positive factors
Three positive factors means N is a prime number.
So, N has two factors. 
Sufficient
 
(2) 2N has four positive factors
N can be 8 or 10
Not sufficient

Option A

Posted from my mobile device

bumpbot · Answer

Automated notice from GMAT Club BumpBot: 

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

 This post was generated automatically.

How many positive factors does positive integer N have?

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Data Sufficiency (DS) Questions

How many positive factors does positive integer N have?

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards