A solid cylindrical rod of brass, 1 m long and 4 cm in diameter, is melted and recast into a hollow spherical shell whose external radius is 9 cm. (Assume no loss of material.)
a. (i) Find the thickness of the shell, correct to two decimal places.
b. (ii) If the density of brass is 8.5g/cm3, calculate the mass of the shell in kilograms, correct to one decimal place.