2016 AMC 12A Problem 5

Below is the professionally curated solution for Problem 5 of the 2016 AMC 12A, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2016 AMC 12A solutions, or check the answer key.

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Concepts:counterexamplelogical deduction

Difficulty rating: 1100

5.

Goldbach's conjecture states that every even integer greater than 22 can be written as the sum of two prime numbers (for example, 2016=13+2003).2016=13+2003). So far, no one has been able to prove that the conjecture is true, and no one has found a counterexample to show that the conjecture is false. What would a counterexample consist of?

an odd integer greater than 22 that can be written as the sum of two prime numbers

an odd integer greater than 22 that cannot be written as the sum of two prime numbers

an even integer greater than 22 that can be written as the sum of two numbers that are not prime

an even integer greater than 22 that can be written as the sum of two prime numbers

an even integer greater than 22 that cannot be written as the sum of two prime numbers

Solution:

A counterexample must satisfy the hypothesis of being an even integer greater than 22 while failing the conclusion that it can be written as the sum of two prime numbers.

Thus, the correct answer is E.

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