the stress strain for an alloy with an average nucleus size of 100 micron

find

1)the modulus of elasticity for the alloy

2) the yielding stress

for 1) i assume that the red line is meant to be at 0.0005 therefore

E=dσ/dε=100e6/0.0005

**E=200Gpa**

for 2) i dont know what i can do, all that i do know is that the slant of the line from ε=0.002 to the point of σ

_{y}is equal to 200Gpa (from the E i found before), but how can i use this to find the stress, i do not know the strain for σ

_{y}, since i was given the nuclesu size i think i must somehow use that, but how??