Definitions Complement rule: P(A^(C))=P(not A)=1-P(A) Addition rule for disjoint or mutually exclusive events: P(A ∪ B)=P(A or B)=P(A)+P(B) Solution The probability P(0<= z<= 1.96) is given in the row with z=1.9 and in the column with .06 of the normal probability table in the appendix: P(0<= z<= 1.96)=0.4750 The probability P(0<= z<= 0.42) is given in the row with z=0.4 and in the column with .02 of the normal probability table in the appendix. The standard normal distribution is symmetric about 0: P(-0.42<= z<= 0)=P(0<= z<= 0.42)=0.1628 Add the corresponding probabilities: P(-0.42<= z<= 1.96)=P(0<= z<= 1.96)+P(-0.42<= z<= 0) =0.4750+0.1628=0.6378