(a) From graph, for stress $=150 \times 10^{6} \mathrm{N} \mathrm{m}^{-2},$ the corresponding strain $=0.002$Young's modulus, $=7.5 \times 10^{10} \mathrm{N} \mathrm{m}^{-2}$(b) Approximate yield strength will be equal to the maximum stress it can sustain without crossing the elastic limitTherefore, the approximate yield strength $=300 \times 10^{6} \mathrm{N} \mathrm{m}^{-2}$$=3 \times 10^{6} \mathrm{N} \mathrm{m}^{-2}$ .