Explain why this method is valid in propagating uncertainty through calculations. Be detailed and specific. Give specific reference to the reading from last week's assignment.

Suppose the mass of the long sheet of paper with uncertainty is $8\mathrm{.}23$ g with uncertainty $0\mathrm{.}01$ g $.$ Determine the mass density and its uncertainty, again using the procedure from the document.

From #$3,$ can you decide whether one of the measured quantities contributes most of the error? If you were able to re$-$do the measurements and focus on improving the precision of only one of them, which would you choose, or are all equally in need of improvement? Justify your answers.