Which of the following statements are correct when deciding whether to use the z or the t distribution?
A.
Use the z distribution in a test of proportions when nπ and n(1 - π) are greater than or equal to 5.
B.
Use the z distribution when we have a normal population and we know the population standard deviation.
C.
Use t when the population is normal and the population standard deviation is not known.
D.
All of the above statements are correct.