Some Q's

Suyog · Posted: Wed Oct 03, 2007 3:52 pm Post subject: Some Q's

1. If r and s are integers, is r2 + s even ?
(1) The product rs is odd.
(2) r is odd.

2. What is the volume of a certain rectangular solid?
(1) Two adjacent faces of the solid have areas 15 and 24, respectively.
(2) Each of two opposite faces of the solid has area 40.

wongee · Posted: Wed Oct 03, 2007 5:07 pm Post subject:

Type yes/No

St 1: Product rs is odd
so, try options or you should know:
Odd X Even = Even
Even X Even = even
Odd X Odd = Odd

If the product rs is odd, the only option is that both r and s are odd. Which now makes r2 + s = OddX2 + Odd = Even + Odd = Always Odd - SUFFICIENT Eliminate BCE

St II: r is odd.
So, r2 +s = Odd X 2 + s = Even +s
But s can be either odd or even giving either a odd or an even result. INSUFFICIENT

Answer Choice A What is the correct answer

Please correct me if I am wrong!