Chapter 9, Problem 21BPS

Masonry A square pillar is built using $15\frac{5}{8}$ in.-square concrete blocks 8 in. high with $1\frac{3}{4}$-in.-thick walls. This creates a hollow square prism inside each block. (See the figure.) If the pillar is 10 blocks high, how many cubic yards of concrete will it require to fill the pillar? (Round to the nearest 0.1 cu yd.)