properties of number

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properties of number

by romitvsingh » Fri Dec 02, 2011 10:22 pm
If i and j are integers, is i + j an even integer?

1) i < 10

2) i = j
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by pemdas » Sat Dec 03, 2011 11:29 am
i+j is even in the following cases
a) i and j are even, b) i and j are odd <- we can answer here Yes here
In all other cases one is even and one is odd we can answer No
Thus, technically this q. doesn't require much solution, as we can select Yes/NO right away

st(1) i<10 can be even or odd, and we don't know about j, Not Sufficient (we can answer both Yes or No, depends on exact values of i and j)
st(2) i=j, these two integers can be even or odd. Sufficient to answer Yes, the resultant is even

b
romitvsingh wrote:If i and j are integers, is i + j an even integer?

1) i < 10

2) i = j
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by LalaB » Sat Dec 03, 2011 11:54 am
romitvsingh wrote:If i and j are integers, is i + j an even integer?

1) i < 10

2) i = j
the question is i+j=even? it is possible only if both i and j are even, or both i and j are odd

stmnt 1 i<10 nothing helps. i and j can be both even ,or one of them can be odd, another one can be even

smnt 2 i=j here u can think in two ways:
-so we have i=j and i+j can be rewritten as i+i=2i (or j+j=2j) 2i (or 2j) is always even (because of 2)

-doesnt matter what a number u have (odd or even), when u add a number to itself, u get an even number. lets test it. if i=2 and i=j 2+2=4 (even). if i=3 and i=j 3+3=6 (even)

so answ is B