Events & Promotions
|
|
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Apr 2808:00 AM PDT
-11:00 AM PDT
Whether you are just beginning your MBA journey or fine-tuning your path to a 700+ score, GMAT Day is designed to give you a competitive edge.
06 May 2021, 10:36
Kudos
Bookmarks
A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
25%
(medium)
Question Stats:
74% (01:10) correct
26%
(01:14)
wrong
based on 50
sessions
History
Date
Time
Result
Not Attempted Yet
Is integer a a prime number?
(1) 2a has exactly three factors.
(2) a is an even number
(1) 2a has exactly three factors.
(2) a is an even number
06 May 2021, 10:45
Kudos
Bookmarks
Bunuel
Question: Is integer a = Prime?
Statement 1: 2a has exactly three factors.
CONCEPT: Number of Factors
For a Number \(N=a^p*b^q*c^r*... \)where a, b, c etc are distinct prime factors of n and p, q r are their respective exponents
The number of factors of \(N = (p+1)*(q+1)*(r+1)*...\) and so on
ie. for a number to have 3 factors it must be of type \(Prime^2\)
i.e. a must be 2
@a = 2, 2a = 4 which has 3 factors
but for any other value of a, 2a will not have 3 factors hence
a = 2
SUFFICIENT
Statement 2: a = even
a could be 2 or 4 or 8 etc, hence
NOT SUFFICIENT
Answer: Option A
WannaManaConsult
06 May 2021, 10:45
Kudos
Bookmarks
1) The only way to get 3 factors is for a number to be a perfect square of a prime number.
2 is a factor of 2a. That means the factors must be 1, 2, 4 and 2a=4. a=2 and is prime. Sufficient
2) a can be any multiple of 2, including 2 itself. 2 itself is prime, no other multiple of 2 is. Insufficient.
2 is a factor of 2a. That means the factors must be 1, 2, 4 and 2a=4. a=2 and is prime. Sufficient
2) a can be any multiple of 2, including 2 itself. 2 itself is prime, no other multiple of 2 is. Insufficient.
