The volume of a cone is calculated through the equation below,
V = πD²h / 12
where V is volume, D is diameter and h is height.
To determine the number of cups, we divide the sink volume by the volume of the cup,
(a.) V = π(4 in)²(8 in) / 12 = 32π/3 in²
number of cups = (2000π/3 in²) / (32π/3 in²) = 62.5 cups or 63 cups
(b) V = π(8 in)²(8 in) / 12 = 128π/3 in²
number of cups = (2000π/3 in²) / (128π/3 in²) = 15.625 cups or 16 cups