Ask Questions, Discuss Approaches & No Clutter

If x is a positive integer greater than 1, is x! + x + 1 a prime number?

Solved 1 Answers 515 Views
GMAT Timer00:00

If x is a positive integer greater than 1, is x! + x + 1 a prime number?

(1) x < 10
(2) x is odd

Official Answer

1 Best Answer

Best answer
Answer: Can be solved using condition 2 Only. (B).
Since x is odd, then x+1 is even and x! is even . Hence x! + x + 1 is even . Hence it cannot be a prime number.
Using the Condition 1 : It cannot be concluded whether it is a prime no or not . eg :
If x = 4 then x! + x + 1 = 29 which is a prime no but if x = 3 then x! + x + 1 = 10 which is not a prime number .
Hence the questions can be answered using statement 2 alone .
answered Jun 22, 2014 by Associate (163 points)
selected Jun 22, 2014 by
Student Speaks

Jyotsna Mehta

Indian School of Business, Co'18

I am very thankful to Gmatxchange and would definitely recommend Gmatxchange mentors to all those students applying for MBA admissions

Your Tentative GMAT Score
Estimate your GMAT score.
The scorer helps you to determine your current level within a few questions you solve.Read More
Please log in or register to use the Scoring Feature
Confused about your profile & colleges, Get FREE profile evaluation today from over 10 consultants.
Follow us and get quick prep updates on Facebook