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30 Mar 2022, 04:30
Kudos
Bookmarks
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
5%
(low)
Question Stats:
90% (01:11) correct
10%
(01:00)
wrong
based on 81
sessions
History
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Not Attempted Yet
If x and y are positive integers, is (x + y) a prime number?
(1) x = 1
(2) y = 2 × 3 × 5 × 7
(1) x = 1
(2) y = 2 × 3 × 5 × 7
31 Mar 2022, 09:46
Kudos
Bookmarks
Bunuel
Given: x and y are positive integers
Target question: Is (x + y) a prime number?
Statement 1: x = 1
No information about the value of y. Not sufficient.
Statement 2: y = 2 × 3 × 5 × 7
No information about the value of x. Not sufficient.
Statements 1 and 2 combined
Statement 1 tells us that x = 1
Statement 2 tells us that y = 2 × 3 × 5 × 7
So, we now know that x + y = 1 + (2 × 3 × 5 × 7)
At this point, we have the exact value of x + y, which means we COULD determine whether that value is prime. Of course, we'd never waste valuable time on test day doing so, since our only task here is to determine whether the combined statements are sufficient to announce the target question. Which they are.
Since we could answer the target question with certainty, the combined statements are SUFFICIENT
Answer: C
Aside: 1 + (2 × 3 × 5 × 7) = 211, which is prime.
So, the answer to the target question is YES, x+y is prime.
Cheers,
Brent
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