Answer:
The difference in volume of the two models is
![(128)/(3)\ in^(3)](https://img.qammunity.org/2020/formulas/mathematics/college/h7f1tyrwt0r74z0i7ih0pmnu98adj1c8td.png)
Explanation:
we know that
The volume of a square pyramid is equal to
![V=(1)/(3)b^(2)h](https://img.qammunity.org/2020/formulas/mathematics/middle-school/uiods2fk5itpg5uz0ac5id5t8lhm0uqqay.png)
where
b is the length of the side of the square base
h is the height of the pyramid
step 1
Find the volume of Amy's model
we have
![b=8\ in](https://img.qammunity.org/2020/formulas/mathematics/college/cwf9cnqardthq096i8o9yumtc18q48pysu.png)
![h=5\ in](https://img.qammunity.org/2020/formulas/mathematics/middle-school/xhy88uem0840wbzvnu9k1ne7r2j907rbnb.png)
substitute
![V=(1)/(3)(8)^(2)(5)](https://img.qammunity.org/2020/formulas/mathematics/college/xzii2f825cpvn6tnmr3i4z294m1hp2xado.png)
![V=(320)/(3)\ in^(3)](https://img.qammunity.org/2020/formulas/mathematics/college/ns0epqin6sp5g5pz93u98q5j5yqr31emom.png)
step 2
Find the volume of Alex's model
we have
![b=8\ in](https://img.qammunity.org/2020/formulas/mathematics/college/cwf9cnqardthq096i8o9yumtc18q48pysu.png)
![h=3\ in](https://img.qammunity.org/2020/formulas/mathematics/college/jipwrxkkyjwx9nlpwkiwl79nsvbeidjv0y.png)
substitute
![V=(1)/(3)(8)^(2)(3)](https://img.qammunity.org/2020/formulas/mathematics/college/q0uge093p5y8p5awuy5gb2rbxamynatwkp.png)
![V=(192)/(3)\ in^(3)](https://img.qammunity.org/2020/formulas/mathematics/college/k1emuo5bjd86f2iufs2jrbq7myf22t0hn8.png)
step 3
Find the difference in volume of the two models
![(320)/(3)\ in^(3)-(192)/(3)\ in^(3)=(128)/(3)\ in^(3)](https://img.qammunity.org/2020/formulas/mathematics/college/holh03wntk43ifqx37zvdd5ejpi60498dh.png)