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100 points for $49 worth of Veritas practice GMATs FREE VERITAS PRACTICE GMAT EXAMS Earn 10 Points Per Post Earn 10 Points Per Thanks Earn 10 Points Per Upvote ## The function f is defined for all integers n by the... tagged by: swerve ##### This topic has 1 expert reply and 0 member replies ### Top Member ## The function f is defined for all integers n by the... The function f is defined for all integers n by the following rule. f(n) is the number of positive integers ecah of which is less than n and has no positive factor in common with n other than 1. If p is any prime, then f(p)=? A. p-1 B. p-2 C. (p+1)/2 D. (p-1)/2 E. 2 The OA is A . Guys, does this questions makes sense to anyone? I am struggling. Does it mean that: f(n) is a list of positive integers. Am I right? for e.g f(5) = 3,4. I am stuck after this. Can any expert help me with this PS question please? ### GMAT/MBA Expert Legendary Member Joined 14 Jan 2015 Posted: 2667 messages Followed by: 122 members Upvotes: 1153 GMAT Score: 770 swerve wrote: The function f is defined for all integers n by the following rule. f(n) is the number of positive integers ecah of which is less than n and has no positive factor in common with n other than 1. If p is any prime, then f(p)=? A. p-1 B. p-2 C. (p+1)/2 D. (p-1)/2 E. 2 The OA is A . Guys, does this questions makes sense to anyone? I am struggling. Does it mean that: f(n) is a list of positive integers. Am I right? for e.g f(5) = 3,4. I am stuck after this. Can any expert help me with this PS question please? The idea is that f(n) = the number of integers that share no common factors with n other than 1. For example, you invoked f(5). So how many integers share no common factors with 5, aside from 1? Well, the integers that share no common factors with 5 would be 1, 2, 3, and 4, giving us a total of 4 numbers. So f(5) = 4. Now simply plug '5' in for 'p' in the answer choices, and see which gives you a value of '4.' The answer is A _________________ Veritas Prep | GMAT Instructor Veritas Prep Reviews Save$100 off any live Veritas Prep GMAT Course

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