The modulus of elasticity

The modulus of elasticity

The modulus of elasticity for boron carbide (B4C) having 5vol% porosity is 290GPa (42 ( 106psi).
(a) Compute the modulus of elasticity for the nonporous material.
(b) At what volume percent porosity will the modulus of elasticity be 235GPa (34 ( 106psi)?