dimmak wrote:
If m, k, x, and y are positive numbers, is \(mx + ky > kx + my\) ?
(1) \(m > k\)
(2) \(x > y\)
First thing I see is that the difference between the sides of the inequality is the position of m,k
This makes me think about MIN-MAX. Also, we don't know the signs of the variables and inequalities are often about what is + or -
1) m > k
This means that: BIG*x + small*y > small*x + BIG*y
We don't have any info about k,m so insufficient
2) x > y
This means that m*BIG + k*small > k*BIG + m*small
Again, no info about the values of x,y so insufficient
3) If we combine:
BIG*BIG + small*small > small*BIG + BIG*small
We can see that the right hand side is bigger, so both together are sufficient, C
Testing values:
x>y
3>2
m>k
3>2
3*3+2*2 > 2*3+2*3
13>12
x>y
-1>-2
m>k
3>2
-1*3 + -2*2 > -2*3 + -1*2
-7>-8
x>y
-1>-2
m>k
-2>-3
-1*-2 + -2*-3 > -2*-2 + -1*-3
8>7