The volume of a prism can be calculated using the following formula, where B is the area of the base and h is the height.
V=Bh
Let's first calculate the area of the base B. We can see that the base is a trapezoid, so we can use the known formula to find its area.
B = 1/2h(b_1+b_2)
From the diagram we can see that h=3in., b_1 = 15in. and b_2=7in. Let's calculate the area of the base.