PeepalTree wrote:

Is \(yz > wz?\)

1. \(y > w\)

2. \(z^3 < z\)

First inequality rearranged to yz - wz > 0 then z (y - w) > 0

Statement 1) tells us y > w and that can be rearranged to y - w > 0

z ( y - w) > 0 we know one part is > 0 but don't know about Z so insufficient.

For Statement 2)

\(z^3 < z\) can be rearranged to \(z > z^3\) then \(z - z^3 > 0\) then \(z (1 - z^2) > 0\)

we know \(z > 0\) and \(1 - z^2\) can be rearranged to square of a difference \((1 - z) (1 + z) > 0\)

so 1 > z and 1 > - z so -1 < z

0 < z < 1 and z > - 1

since we have no information on (y-w) we cannot tell.

Insufficient.

Now combine both.

we know from first statement (y-w) is positive.

We also know from second statement that z can be positive or negative for example z can be 1/2 or -1/2

Insufficient.

Answer choice E