Question 53501
Density=mass/volume {{{highlight(D=m/V)}}}
The volume of the glass is lenght*width*height
m=35.303 g
The thickness of the glass is not in the right units, it needs to be in cm's like the rest of the dimensions before you multiply.
{{{2.2cross(mm)*1cm/cross(10mm)=.22cm}}}
{{{V=7.61cm*7.68cm*.22cm=12.857cm^3}}}
{{{highlight(D=35.303g/12.857cm^3=2.7458(g/cm^3))}}}
Double check this on your calculator, I'm human, not a computer.  Math is my thing, and this is a science question.  Also some books use kg/m^3 as the prefered unit.  Make sure that g/cm^3 is an acceptable unit.
Happy Calculating!!!