DarkHorse2019 wrote:
Shef08 wrote:
Hi I need help on this one. Can any of the experts look in to this..
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Dear Moderators
chetan2u VeritasKarishma Bunuel Gladiator59 generisPlease can you explain this one?
I did not understand why A1 & A2 have to be both odd or both even.
The question tells you that A3 is a positive integer.
A3 = (A1 + A2)/2 = Integer
This means (A1 + A2) = 2*Integer = Even Integer
When will sum of two numbers be even? When both are even or both are odd.
Even + Even = Even
Odd + Odd = Even
Even + Odd = Odd
So A1 and A2 are both either even or both odd. Anyway, it doesn't matter.
You know that A1, A2 and A3 all are integers. A4 may not be an integer.
A4 = (A2 + A3)/2
A5 = (A3 + A4)/2 = [A3 + (A2 + A3)/2]/2 = (3*A3 + A2)/4
Since A2 and A3 are integers, you cannot have 8 in the denominator.
Answer (D)
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Karishma
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