The probability that the the sample mean would be less than x=132.25 will be calculated as follows: z=(x-σ)/μ μ- mean σ- standard deviation z=(132.25-138)/28=-0.2054 thus: P(X≤x)=0.4207=42.07%
I believe when studying, you should read and study as much information as you can, textbooks, Notes, research, ETC. Studying is for you to put everything you have learned into one. ~Hope This Helped~
