1. The problem statement, all variables and given/known data Let [tex]\psi[/tex](x) = 2[tex]\phi[/tex](x) - 1. The function [tex]\psi[/tex] is called the positive normal distribution. Prove that if Z is standard normal, then |Z| is positive normal. 2. Relevant equations 3. The attempt at a solution I am not really sure where to begin with this. Can anyone provide me a jumping off point, please? I do know that [tex]\phi[/tex](-x) = 1 - [tex]\phi[/tex](x) and so [tex]\phi[/tex](x) + [tex]\phi[/tex](-x) - 1 = 0. I am not sure how to utilize that or if it is even on the right track. Thanks for any help.