I have been a silent reader of this forum from last few months,just passed naplex so wanted to share my experience with you all.
I read APHA primarily.But its true that it does not cover everything asked in naplex,so I took help from CPR,Remington.For maths I used stoklosa mainly.In Naplex, I had Qs from all major topics of APHA and atleast 8 Statistics Qs. Apart from Statistics, I had approximately 18-20 math Qs, which were mixed some easy some tough ones.
My recommendation is to practice a lot Questions from some good practice site so that you can have idea about different types of questions asked in naplex.
I used all the practice tests from chasenaplex and prenaplex (2 times), and appleton and lange they had pretty good question similar to the pattern of naplex.
Good luck and thanks for the wishes