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Answer Explanations for: SAT January 2013

This page contains answer explanations to every question from the January 26, 2013 SAT, Form Codes AEJA, BWJA. Many Mathematics and Writing explanations also link to content pages that explain the relevant grammatical and mathematical concepts in greater detail. Please note that this page will contain the explanations only, and will not provide the test questions themselves; it is a tool intended for use with a copy of your test that you purchased from the College Board via the Question and Answer Service (QAS). The following are sample explanations:

Section 2: Mathematics
6) C) 2 is the only even prime number, so p must be an odd number. For the same reason, the prime number represented by the expression in the correct answer must also be odd. Therefore, B and D can be eliminated because adding two odd numbers produces an even number. Similarly, E can be eliminated since it must be an even number; because p is odd, 5p must also be odd, since an odd times an odd is always odd, so 5p + 1 must be even. Answer choice A can be eliminated since 3p would have 3 and p as factors, and the only factors of a prime number are 1 and itself. Therefore, by process of elimination, C is the only possible prime number, since it is an odd number with no known factors. See number properties.