megafan wrote:
If k is a multiple of 3 and \(k = (m^2)n\), where m and n are prime numbers, which of the following must be a multiple of 9?
(A) \(m^2\)
(B) \(n^2\)
(C) \(mn\)
(D) \(mn^2\)
(E) \((mn)^2\)
Source: Gmat Hacks 1800
must be a multiple of 9m and n are prime...lets have 2 and 3
now either of then can be a 3...
a) m can be 2 and n = 3...out
b) n can be 2 and m = 3...out
c) m = 2 and n=3 ...out
d) n can be 2 and m = 3...out
e) m = 2/3 or n = 3/2 both satisfies .......must be a multiple of 9
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70% (01:32) correct 
