Is x a prime number? (1) x is an even number. (2) x cannot be divided

yeah right.
missed it completely.

This is more of a "don't overthink too much question" than anything else.
is x prime?

(1) x is even. X could be 2, hence prime. But also 4,6,8,...IS
(2) x can not be divided evenly by an odd number other than 1. This is tempting but the statement says nothing about even numbers. So x could be even! (I see what you did there).

Together it basically stays the same. From (2), x could be be even and from (1) we only get that x is even, hence still IS.

E.

Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.


Is x a prime number?

(1) x is an even number.
(2) x can not be divided evenly by an odd number other than 1.

In the original condition, there is 1 variable(x), which should match with the number equation. So you need 1 more equation. However, for 1) 1 equation, for 2) 1 equation, which is likely to make D the answer.
In 1), x=2 -> yes and x=4 -> no, which is not sufficient.
In 2), x=2 -> yes and x=4 -> no, which is not sufficient. Even when 1) & 2), ), x=2 -> yes and x=4 -> no, which is not sufficient. Therefore, the answer is E.


-> For cases where we need 1 more equation, such as original conditions with “1 variable”, or “2 variables and 1 equation”, or “3 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 59 % chance that D is the answer, while A or B has 38% chance and C or E has 3% chance. Since D is most likely to be the answer using 1) and 2) separately according to DS definition. Obviously there may be cases where the answer is A, B, C or E.

1) x could be 2, which is a prime or x could be 4 which is not a prime. Not Sufficient.

2) This statement tells us that x has no odd factors other than 1, so x is even (In fact, we may also conclude that x is a power of 2). This statement provides same info as statement 1. Not Sufficient.

Statement 1 and 2 give the same information, so combined together these statements are not sufficient.

my answer would be E.

Statement 1
x is an even number
If x = 2, then x is a prime (yes)
If x = 4, then x is not a prime (no)
Insufficient

Statement 2
x can not be divided evenly by an odd number other than 1
Same cases as statement 1 above - Insufficient.

Statement 1 and 2
Same cases as statement 1 above - Insufficient.

Answer - E

Bunuel,

When we say - divide "evenly"- do we mean that the number should be divided in even factors? for example 9 (an odd) number can be divided by 3 bit there is no even factor. so, can we say that 3 divides 9 evenly? or only when a number has an even factor then we can say that number is "evenly" divided? Answer to this question will play a major role in solving above question.

Regards
Yash

Divide evenly simply means divides without a remainder, so we can say that 3 divides 9 evenly because 9/3 = 3, no remainder.

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.