To determine the change in the water level after the aluminum is added, we sum up the forces acting on the piece aluminum. In this case, the weight of the piece is equal to the buoyant force. We do as follows:
W = Fb
mg = m(water)g
m = m(water)
40 = density of water ( volume )
40 = (1) V
V = 40 mL
Therefore, 40 mL of volume is being displaced by the aluminum and the level would be at about 90 mL.