Lesson: Prime Factorization

Comment on Prime Factorization

hi
would you plz help me with this

If K is an integer and 2 < k < 8, what is the value of k?

1) k is a factor of 30

2) k is a factor of 12.

my answer was c
the prime factorization for 30 is 2-3-5
for 12 is 2-2-3
so just 3 between them so it is c
what is the wrong here?
gmat-admin's picture

Be careful. The question does not say that "k is a PRIME factor of 30." It just says "k is a factor of 30."

Statement 1: The factors of 30 are: 1, 2, 3, 5, 6, 10, 15, 30.
Since we're told that 2 < k < 8, we can conclude that k = 3, 5 or 6
INSUFFICIENT

Statement 2: The factors of 12 are: 1, 2, 3, 4, 6, 12.
Since we're told that 2 < k < 8, we can conclude that k = 3, 4 or 6
INSUFFICIENT

The two statements COMBINED
Statement 1 tells us that k = 3, 5 or 6
Statement 2 tells us that k = 3, 4 or 6
Since both statements must be true, we can see that k can still equal 3 or 6.
INSUFFICIENT

Answer: E

Dear Brent,
If I try to open the
GMAT practice question (difficulty level: 650 to 800) – e-GMAT
question it always says: You are not authorized to read this forum.
gmat-admin's picture

Thanks for the heads up!
I have removed the broken link.

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