The hydrometer shown in figure is a device for measuring the density of liquids. The bulb contains lead shot, and the density can be read directly from the liquid level on the stem after the hydrometer has been calibrated. The volume of the bulb is 20mL, the stem is 15 cm long and has a diameter of 5.00 mm, and the mass of the glass is 6.0 g.

(a) What mass of lead shot must be added so that the least density of liquid that can be measured is 0.9 kg/L?

(b) What is the maximum density of liquid that can be measured?