Question

I'm not sure about my answers for b), c) & d). Am i right?

Answer 1

@amistre64

Answer 2

the sampling distribution of the sample means are normally distributed, that is the basis of the central limit thrm

the sample mean is an estimate of the population mean

and the sample standard deviation is a division by sqrt(n) of the population "sd"

the rest of it is of course using those as the parameters to find the probabilities

Answer 3

z > (90.9 - 87)/3; 1.3
z <= (80.1 - 87)/3; -2.3

(85.2 - 87)/3 < z < (92.25 - 87)/3
-.06 1.75

a normalCDF function would take care of those, or table it as needed

Answer 4

0.0968
0.0107

9599
- 4761
------
0.4838