Answer:
a
The volume of the aluminum is 
b
The buoyant force exerted is
From the question we are told that
The mass of the aluminum is 
The density of the aluminum is 
Generally volume is mathematically represented as

Substituting values accordingly

Generally buoyant force is mathematically represented as

Where V is the volume of the aluminum
is the density of water 
g is the acceleration due to gravity = 
Substituting these values accordingly we have

