Mean proportion of individuals is p=0.30, sample size is 25 from this population, what fraction will have a sample porportion of 0.20 or lower?
Welcome to the forum.
I see you have posted several questions that involve the normal distribution. I have just written out some background on this for another poster and he was able to get the right answer.
You might find it helpful to view his post:
The help for Q3 starts at post number 17.
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei