Given X1,X2∼N(0,1)X_1, X_2 \sim N(0, 1)X1,X2∼N(0,1) i.i.d., find P(X1+X2>0)P(X_1 + X_2 > 0)P(X1+X2>0).
0.5
0.25
0.75
0.33