Here;
From the question we can assume QTY A > QTY B

let us assume 1.9 = 2 and 1.999 = 2

Now QTY A = \(2^3 = 8\)

and QTY B = \(2^2 =4\)

Moreover 1.999 will always be less than 2 , similarly 1.9 will always be less than 2

But cube root > square root.

If the question tells us compare between \((1.9)^2\) and \((1.999)^2\) then in this case \((1.999)^2 > (1.9)^2\). This is because the roots of both the QTY are same and 1.999 is more close to 2 than 1.9
_________________

Hello from the GRE Prep Club BumpBot!

Thanks to another GRE Prep Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.