Lesson: Prime Factorization

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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


Hi Brent,

I think the last answer choice has a mistake? "332" has "2" distinct primes.

Which of the following numbers has the greatest number of distinct prime factors?

A. 165
B. 192
C. 228
D. 330
E. 332
This requires us to find the prime factorization of each answer choice

A. 165 = (3)(5)(11) --- 3 distinct prime factors
B. 192 = (2)(2)(2)(2)(2)(2)(3) --- 2 distinct prime factors
C. 228 = (2)(2)(3)(19) --- 3 distinct prime factors
D. 330 = (2)(3)(5)(11) --- 4 distinct prime factors
E. 332 = (2)(2)(83) --- 3 distinct prime factor

Hi Brent,

This was one of the links posted for this vid: https://gmatclub.com/forum/stonecold-s-mock-test-217160.html

Are there any questions from here that you suggest we focus on? Or should we just save the set for further refining post answering the other links?

Many thanks,
Neel
gmat-admin's picture

Hi Neel,

I don't see a link to https://gmatclub.com/forum/stonecold-s-mock-test-217160.html from any of the above links.

With the links in the Reinforcement Activities boxes, I suggest that you answer as many as you feel are necessary to get to the level of expertise you need to achieve your target score.

For some students, this will mean answering a handful of questions in the 500-650 range. For others, it will mean answering all of the questions in the 650 range, etc.

Does that help?

Cheers,
Brent

Oops! In that case I must have clicked it erroneously

Definitely, thank you for clarifying!

Best,
Neel

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