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06 Jul 2017, 07:29
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B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
55%
(hard)
Question Stats:
57% (01:35) correct
43%
(01:47)
wrong
based on 313
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If x is a prime number, what is the number of different factors of 18x?
1) x^2 has 3 factors
2) x>3
1) x^2 has 3 factors
2) x>3
Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.
For relevant Data Sufficiency questions, please check the Data Sufficiency forum:
https://gmatclub.com/forum/data-sufficiency-ds-141/
https://gmatclub.com/forum/data-sufficiency-ds-141/
06 Jul 2017, 09:01
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If x is a prime number, what is the number of different factors of 18x?
18x can be written as 2 * 3^2 * x
Case 1: If x=2, then 18x = 2^2 * 3^2 , total number of factors = 3*3 = 9
Case 2: If x=3, then 18x = 2 * 3^3 , total number of factors = 2*4 = 8
Case 3: If x= a prime number other than 2 and 3, then 18x = 2 * 3^2 * x , total number of factors = 2*3*2 = 12
So we need to find out what is the value of x?
Statement 1) x^2 has 3 factors
Square of any Prime number will have 3 factors. Eg. 2^2, 3^2, 5^2. As this statement gives no new information. This statement is not sufficient.
Statement 2) x>3
This statement clearly tells us that x is greater than 3, which means the third case is applicable here.So the total number of factors = 12. This statement is sufficient.
Answer is B
18x can be written as 2 * 3^2 * x
Case 1: If x=2, then 18x = 2^2 * 3^2 , total number of factors = 3*3 = 9
Case 2: If x=3, then 18x = 2 * 3^3 , total number of factors = 2*4 = 8
Case 3: If x= a prime number other than 2 and 3, then 18x = 2 * 3^2 * x , total number of factors = 2*3*2 = 12
So we need to find out what is the value of x?
Statement 1) x^2 has 3 factors
Square of any Prime number will have 3 factors. Eg. 2^2, 3^2, 5^2. As this statement gives no new information. This statement is not sufficient.
Statement 2) x>3
This statement clearly tells us that x is greater than 3, which means the third case is applicable here.So the total number of factors = 12. This statement is sufficient.
Answer is B
16 Jul 2018, 19:14
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roastedchips
the answer would depend on if x is a factor of 18, that is if x is 2 or 3
If x is 2 or 3, Ans will be different ..
- a) x=2, 18*2=\(2^2*3^2....(2+1)(2+1)=3*3=9\)
b) X=3, 18*3=2*3^3.......(1+2)(3+1)=3*4=12
- \(18x=2*3^2*X.......(1+1)(2+1)(1+1)=2*3*2=12\)
1) \(x^2\) has 3 factors.
Just tells us that \(x^2 is square of a prime number\)
This is already known
Insufficient
2) X>3
now X is a prime number >3
Irrespective of the value of X, factors of 18x will be
18x=2*3^2*X
So factors are (1+1)(2+1)(1+1)=2*3*2=12
Sufficient
B
