For some metal alloy, a true stress of 415MPa (60,175psi)

For some metal alloy, a true stress of 415MPa (60,175psi) produces a plastic true strain of 0.475. How much will a specimen of this material elongate when a true stress of 325MPa (46,125psi) is applied if the original length is 300 mm (11.8 in.)? Assume a value of 0.25 for the strain-hardening exponent n.