A cylindrical specimen of a metal alloy 48.0 mm long and 9.72 mm in diameter is stressed in tension. A true stress of 368 MPa causes the specimen to plastically elongate to a length of 53.5 mm. If it is known that the strain-hardening exponent for this alloy is 0.2, calculate the true stress (in MPa) necessary to plastically elongate a specimen of this same material from a length of 48.0 mm to a length of 57.4 mm.