(Paper thickness problem)
The thickness of one sheet of laboratory filter paper is measured to be 0.125mm. Four identical sheets are stacked one upon another.
a. (i) Express the thickness of a single sheet in metres, writing the answer in scientific notation and keeping the appropriate significant figures.
b. (ii) Express the same single-sheet thickness in micrometres (μm) in scientific notation.
c. (iii) Calculate the combined thickness of the four-sheet stack in metres and write the result in scientific notation, limiting the answer to the correct number of significant figures.