Hi. Can someone please help me with this problem?

A rectangular block of metal weighs 3 oz. How many lbs will a similar block of the same metal weigh if the edges are twice as long?

4 answers

think of it this way...
let the original edge be x units long
so x^3 = 3 oz

then the new edge would be 2x units and
(2x)^3 or 8x^3 would be the new volume.

so it is 8 times the original mass or 24 oz.
Where do you get the x^3 from?
volume = length x width x height
so volume = (x)(x)(x) = x^3

(2x)^3 = (2x)(2x)(2x) = 8x^3
Thanks!