Question 1203213
population mean is 25
population standard deviation is 4
sample size is 25
sample mean is 24
you want to know the probability that the mean time spent on academic activities is less than 24 hous per week.


z = (x - m) / s
z is the z-score
x is the smaple mean
m is the population mean
s is the standad error.


standard error = standard deviation / sqrt(sample size) = 4 / sqrt(25) = 4/5 = .8
z-score formula becomes:
z = (24 - 25) / .8 = -1/25.


area to the right of z-score of -1.25 = .89435
that's the probability that the mean time spent on academic activitie is at least 24 hours per week.


here's what it looks like on a normal distribution graph.


<img src = "http://theo.x10hosting.com/2023/080801.jpg">