Hi all,
First let's revise some baisc rules regarding addition, subtraction, division and multiplication of odd and even numbers :
Odd + Odd = Even
Even + Even = Even
Even + Odd = Odd
Odd - Odd = Even
Even - Even = Even
Even x Even = Even
Odd x Even = Even
Odd x Odd = Odd
Even/Odd = Even
Odd/Odd = Odd
Even/Even = Odd or Even
Now, coming back to the question,
We know that set Q contains more than 2 numbers
Statement 1:
As per the rules discussed above we can see that the sum of two odd numbers will be even and the sum of two even numbers will also be even.
There is no way to find out if the numbers are odd or even, thus statement 1 alone is not sufficient.
Statemnet 2:
As we can see in the above mentioned rules that if one out of the two numbers is even then the product is also even
There is no way to find out if the second number is odd or even, thus, statemnet 2 alone is also not sufficient
Statement 1 and 2 together:
In this case we know that the sum as well as product of any two numbers from the set is even:
If one number is odd and the other is even, then the product will be even but the sum will be odd, thus this can't be the case
If both numbers are odd, then the sum will be even but the product will be odd, thus this can't be the case either
If both numbers are even then the product as well as the sum will be even, as this is the only case that gives us a definate answer of all the numbers in set Q being even, we can safely conclude that the correct answer to this question is:
Option C) BOTH statements TOGETHER are SUFFICIENT.
Hope this helped!
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