kman
Is m + z > 0?
(1) m - 3z > 0
(2) 4z - m > 0
Hi
BunuelHelp me with what is wrong in my approach
Q.Stem : is m+z>0
Since we dont know anything about m and z we cannot do anything with the stem.
m/z can be 0/+ve/-ve
Statement 1: m-3z>0 ==> m>3z
Let z=0 ==> 3z=0 ==> m>0, let m=1 ==> m+z = 1+0 = 1 > 0 (YES)
Let z=1 ==> 3z=3 ==> m>3, let m=4 ==> m+z = 4+1 = 5 > 0 (YES)
Let z=-1 ==> 3z=-3 ==> m>-3. let m=-2 ==> m+z = (-2)+(-1) = -3 < 0 (NO)
INSUFFICIENT
Statement 2: 4z - m > 0 ==> 4z>m ==> m<4z
Let z=0 ==> 4z=0 ==> m<0, let m=-1 ==> m+z = -1+0 = -1 < 0 (NO)
Let z=1 ==> 4z=4 ==> m<4, let m=3 ==> m+z = 3+1 = 4 > 0 (YES)
Let z=-1 ==> 4z=-4 ==> m<-4. let m=-5 ==> m+z = (-5)+(-1) = -6 < 0 (NO)
INSUFFICIENT
Combining 1 and 2
We get, m>3z and m<4z, let m=3.5z ==> m+z = 3.5z+z = 4.5z
Let z=0 ==> 4.5z = 0 ==> 0 = 0 (NO)
Let z=1 ==> 4.5z = 4.5 ==> 4.5 > 0 (YES)
Let z=-1 ==> 4.5z = -4.5 ==> -4.5 < 0 (NO)
INSUFFICIENT
Hence (E)