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.
Some Q's
This topic has expert replies
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!
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!