Consider a flat plate of some alloy that is to exposed to repeated tensile compressive cycling in which the mean stress is 25 MPa. If the initial and critical surface crack lengths are 0.15 and 4.5 mm, respectively, and the values of m and A are 3.5 and 2*10^-14, respectively (for change in stress in MPa and a in m), estimate the maximum tensile stress to yield a fatigue life of 2.5*10^7 cycles. Assume the parameter Y has a value of 1.4, which is independent of crack length.