Question 885586
you got the first part correct.
for the second part:
pm = population mean
psd = population standard deviation
n = sample size
sm = sample mean
se = standard error


in this problem:
pm = 3
psd = 1.2
sm = 2.7
n = 50
se = psd / sqrt(n) = 1.2 / sqrt(50) = .1697
z = (sm - pm) / se = (2.7 - 3) / .1697 = -.3 / .1697 = -1.77


from the z score table, area to the left of -1.77 = .0384


since you want to know the probability of getting a sample mean less than 2.7 hours, you want the area to the left of the z score.


your answer is that the probability is equal to .0384.


the z score table i used can be found here:
<a hrer = "http://lilt.ilstu.edu/dasacke/eco148/ztable.htm" target = "_blank">http://lilt.ilstu.edu/dasacke/eco148/ztable.htm</a>