Answer:
First you find the volume of the pyramid:
1. find the area of the base:
A= 15 x 5= 75
2. Multiply the Area of the rectangle by the height; h= 12 and si use the result by 3.
V= A x h /3 =. 75 x 12 = 900 /3
V= 300
3. If only 1/2 is filled, that means
V= 300/2= 150 in3 is filled and
150 in3 of marbles is needed to fill the container.