how do i find this out

Answer:
The volume is 4908.75 ft³.
Step-by-step explanation:
Don't think about it as a block. Remember the rule for volumes of prisms: cross sectional area times length.
In this case, the cross section is a trapezium, so let's find the area for it:
[tex]a = \frac{13.1 + 25.4}{2} \times 17 \\ a = 19.25 \times 17 \\ a = 327.25[/tex]
Now, multiply it by the length to get the volume:
[tex]v = 327.25 \times 15 \\ v = 4908.75[/tex]