500 ps test22 #10

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500 ps test22 #10

by dunkin77 » Sun Apr 15, 2007 10:21 am
Hi,

I thought the answer is E) but the correct answer is C)....Can anyone explain why? :? Thanks.

10. The numbers in which of the following pairs do NOT have a pair of distinct prime divisors in common ?
(A) 10 and 20
(B) 12 and 18
(C) 24 and 32
(D) 21 and 63
(E) 22 and 88

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Re: 500 ps test22 #10

by jayhawk2001 » Sun Apr 15, 2007 11:58 am
dunkin77 wrote:Hi,

I thought the answer is E) but the correct answer is C)....Can anyone explain why? :? Thanks.

10. The numbers in which of the following pairs do NOT have a pair of distinct prime divisors in common ?
(A) 10 and 20
(B) 12 and 18
(C) 24 and 32
(D) 21 and 63
(E) 22 and 88
Common prime divisors for

A - 2, 5
B - 2, 3
C - 2
D - 3, 7
E - 2, 11

Hence C

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by Kuba » Tue Apr 17, 2007 2:02 am
Hey dunkin77, sorry, it's not about the questions, but it seems that whenever the answer is C, you pick E. So you know what the fastest way of solving those questions for you should be, right? :wink:

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by Cybermusings » Wed Apr 18, 2007 9:12 am
10. The numbers in which of the following pairs do NOT have a pair of distinct prime divisors in common ?
(A) 10 and 20
(B) 12 and 18
(C) 24 and 32
(D) 21 and 63
(E) 22 and 88

a)10- 2&5; 20-2&5
b)12-2&3; 18-2&3
c)24-2&3; 32-2
d)21-3&7 ; 63-3&7
e)22-11&2 ; 88-2&11

Hence answer here is Choice C[/b]