Talking in very Basic Terms
Given, xy>10,000
to find : xz<1000
1. z% of y is 10
yz =1000
thus, y =1000/z
from given eqn : x*(1000/z) > 10,000
x/z>10...........(1')
cant go anywhere with this
2. z is less than 10% of y
z<y/10
so, y>10z
Insuff.
Combine
From (2)
y>10z
multiply both sides by z
yz> 10* z^2
and from (1) yz = 1000
so, 1000> 10*z^2
z^2<100..........(2')
Now From (1'), we had simplified a ratio : x/z > 10
so multiply this inequation with Max of (2')
xz<1000
So C
This is a good Question.
since x,y,z are positive the signs of the inequation will not change. However, if nothing was given about x,y,z, this question would have been way too tough to crack.
