ANSWER;
In addition the "derived quantity", density, will be studied. Make each measurement as accurately as you can, within the limitations of the measuring instrument that you are using. Be sure that the way you record and report this measurement correctly shows the degree of accuracy in the measurement. For example, a meter stick is marked off at intervals of 0.1 of a centimeter, so you can make measurements that are accurate "to the nearest tenth centimeter", or, if you interpolate (estimate between the lines), to the nearest 0.01 or 0.02 cm. If an object that you measure with this meter stick seems to have a length of "exactly" 5 cm, the length should be reported as 5.0 cm (or 5.00 cm if you are interpolating). You should not report the length as 5 cm or 5.000 cm.