collection of tough problems from G PREP - 34

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by sanju09 » Mon Feb 08, 2010 3:40 am
abhasjha wrote:.if the integers a and n are greater than 1 and the product of the first 8 positive integers is a multiple of a^n, what is the value of a?

(1) a^n = 64

(2) n = 6
We have k*a^n = 8!, k is a positive integer constant and the integers a and n are greater than 1. What is a?

(1) For the integers a and n greater than 1, we have more than one way to show that a^n = 64; 2^6 = 64, 4^3 = 64, and 8^2 = 64. Insufficient

(2) If n = 6, a^6 can be a factor of 8! for both rational and irrational a. Insufficient

Combine the two

n = 6 is possible only when a = 2.

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by ajith » Tue Feb 09, 2010 4:07 am
abhasjha wrote:.if the integers a and n are greater than 1 and the product of the first 8 positive integers is a multiple of a^n, what is the value of a?

(1) a^n = 64

(2) n = 6

Product of first 8 positive integers = 8! = 2*3*4*5*6*7*8 = 2^7*3^2*5*7

is a multiple of a^n

1) a^n =64 seems like a weird choice since 8! is not a multiple of 64
2) n=6 also doesnt help

Please check the question
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by sanju09 » Tue Feb 09, 2010 4:23 am
ajith wrote:
abhasjha wrote:.if the integers a and n are greater than 1 and the product of the first 8 positive integers is a multiple of a^n, what is the value of a?

(1) a^n = 64

(2) n = 6

Product of first 8 positive integers = 8! = 2*3*4*5*6*7*8 = 2^7*3^2*5*7

is a multiple of a^n

1) a^n =64 seems like a weird choice since 8! is not a multiple of 64
2) n=6 also doesnt help

Please check the question
But 8! is a multiple of 64 or 2^6.
The mind is everything. What you think you become. -Lord Buddha



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by girish3131 » Thu Feb 11, 2010 12:19 am
acc to me Ans is B

@ Abhasjha

PLZ DONT FORGET TO PUT OA ALSO