<p>A cubical block of metal weighs 6 pounds. How much will another cube of the same metal weigh if its sides are twice as long?</p>
<p>A. 48
B. 32
C. 24
D. 18
E. 12 </p>
<p>The answer is 48, but I would like to know how to work it.</p>
<p>I’m not sure if this is the right way, but if you assume that the weight is related to the volume…</p>
<p>x^3:6(weight of cube #1)=8<em>x^3(replace x with 2x,since the sides are twice as long):y(weight of cube #2)
48</em>x^3=x^3*y
y=48</p>
<p>I always taught my kids that if you are stumped with a math question like this, plug in simple numbers and see what happens. in this case, say the cube is 1 x 1 x 1. It is then 6 lbs per cubic unit. If you double each of those to 2 x 2 x 2 it would be 8 cubic units x 6 lbs per cubic unit = 48 lbs.</p>
<p>I tried this and it worked out…
since, we know that the area of a cube=s^3
From that i plugged in 2 for the orginal cube and found the area to=8
I then realized that the area and weight were directly related so i increased the size of the second square by 2 and the area=64. The area increased by a factor of 8. And since the weight and area are proportional i increased the wieght by a factor of 8 and got 48.</p>
<p>^You meant volume, not area.</p>