Using the normal distribution table we have to find out the value of z corresponding to P where P-(1-P)=0.12. This means graphically that we look at the small and large portions of the distribution (areas under the curve) and take the smaller from the larger so that the resultant area is 12% or 0.12. So 2P-1=0.12, and P=1.12/2=0.56. If we look up 0.56 in the body of the table we find the z score is about 0.15.