Math Problem

Run into a little math problem lately, who would thought math will be part of my life. lol
Anyways, I just got a new laser printer and I need to print something on thicker paper. The max my printer can take is 46 lbs paper.

Now, this is the problem, i got some paper, but i don't know how thick they are. I need to know if they are ok to be print on. (No, it doesn't say on the package) So I took another pack of paper (lets call this pack "A") and measure it, its 6cm high, 500 sheets and its 24 lbs. The new thick paper (let call this "B") measure 1 cm and its only 50 sheets. And yes both paper is the same size.

So you still with me?

A: 6 cm / 500 sheets / 24 lbs
B: 1 cm / 50 sheets / X lbs

Now if all this information, can I calculate how much the thick paper "B" weight?

A bit inform about the paper weight. 20 lbs paper doesn't mean it weight 20 lbs. 20 pound bond paper is always lighter and thinner than 32 pound bond, no matter what its cut size. And 20 pound bond letter size and 20 pound bond legal size papers are the same weight paper having different cut size.
Confuse enough? here abit more reading about paper density : http://en.wikipedia.org/wiki/Paper_density

So yeah, can I even figure out the weight of the thick paper? I did some calculating, got 40 lbs, but not sure if it right. See kids, math will always come back and haunt you!