We will first find the volume of the base:
V 1 = 9² · 5 = 81 · 5 = 405 in³
Then the volume of the upper solid - pyramid. We must find the height of the pyramid:
h² = 11² - 4.5² = 121 - 20.25 = 100.75
h = √100.75
h = 10.037429
V 2 = 1/3 · 9² · 10.037429 = 271.01
Finally, the volume of the composite solid:
V = V 1 + V 2 = 405 + 271.01 = 676.01
Answer: C. 676.01 in³