Problem Solving

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Problem Solving

by dtweah » Tue May 26, 2009 3:59 pm
A certain club has exactly 5 new members at the end of its first week. Every subsequent week, each of the previous week's new members (and only these members) brings exactly x new members into the club. If y is the number of new members brought into the club during the
twelfth week, which of the following could be y?

(A) (5)^1/12

(B) (3^11) 5^11

(C) (3^12) 5^12

(D) (3^11) 5^12

(E) 60^12

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by DarkKnight » Tue May 26, 2009 6:22 pm
The number of new members at the end of 12th week = 5*X^11. Checking the answer choices only D could be expressed as 5*(5*3)^11, hence x=15.

Therefore, Answer=D.