Given:
Rectangular pyramid
length: 3 units
width: 2 units
height: 6 units
scale factor: 4
length : 3 x 4 = 12 units
width: 2 x 4 = 8 units
height: 6 x 4 = 24 units
Volume of a rectangular pyramid = lwh/3
V larger pyramid = (12 * 8 * 24)/3
V = 2304 / 3
V = 768 cubic units