Question $9(1$ point$)$

A large flat plate is subjected to constant$-$amplitude uniaxial cyclic tensile stresses of a maximum stress of $115$ and a minimum stress of $23$ MPa $.$ If before testing the largest surface crack is $0\mathrm{.}93$ mm and the plain$-$strain fracture toughness of the plate is $34\mathrm{.}9MPa{m}^{\frac{1}{2}},$ estimate the fatigue life of the plate in cycles to failure. For the plate, $m=3\mathrm{.}6$ and $A=5\mathrm{.}0{10}^{-12}$ in MPa and meter units. Assume $Y=1\mathrm{.}67$