please answer in order

If the hydrometer is to be constructed with a cylindrical floating rod. Nine fiduciary marks are to be placed along the rod to indicate densities of 0.98 g/cm', 1.00 g/cm", 1.02 g/cm", 1.04 g/cm".... 1.14 g/cm'. The row of marks is to start 0.200 cm from the top end of the rod and end 1.80 cm from the top end. Determine (2.2) The required length of the rod (2.3) The average density? (2.4) should the marks be equally spaced? Explain your