BTGModeratorVI wrote: ↑Fri May 29, 2020 6:28 am
If integer p is a factor of 42, is p a prime number?
(1) p > 6
(2) p < 21
Answer:
E
Source: GMAT prep
Given: Integer p is a factor of 42
The positive factors of 42 are:
1, 2, 3, 6, 7, 14, 21, 42
Target question: Is p a prime number?
Statement 1: p > 6
So, p can equal any of the following values:
7, 14, 21, 42
If n = 7, the answer to the target question is
YES, p is prime
If n = 14, the answer to the target question is
NO, p is not prime
Since we cannot answer the
target question with certainty, statement 1 is NOT SUFFICIENT
Statement 2: p < 21
So, p can equal any of the following values:
1, 2, 3, 6, 7, 14
If n = 7, the answer to the target question is
YES, p is prime
If n = 14, the answer to the target question is
NO, p is not prime
Since we cannot answer the
target question with certainty, statement 2 is NOT SUFFICIENT
Statements 1 and 2 combined
We can already see that n = 7 and n = 14 satisfy BOTH statements. In other words:
If n = 7, the answer to the target question is
YES, p is prime
If n = 14, the answer to the target question is
NO, p is not prime
Since we cannot answer the
target question with certainty, the combined statements are NOT SUFFICIENT
Answer: E
Cheers,
Brent
