Answer:
750 ft^3
Explanation:
Given that the cones are similar, the first step would be to determine their linear scale factor; That is the ratio of their radii;

The next step is to determine the volume scale factors. Since the linear scale factor is 2.5, the volume scale factor would be;
volume scale factor = (linear scale factor)^3
= 2.5^3 = 125/8
The volume of Cone B will thus be;
volume of Cone A * volume scale factor = 48 * 125/8 = 750 ft^3