If the sampled population has a normal distribution, when is the sampling distribution of the sample mean X also a normal distribution ?

Only when the sample size is at least 30.

Only when the sample size is at least 100.

Only when the sample size is smaller than 30

If the sampled population has a normal distribution, when is the samp

1.	If the sampled population has a normal distribution, when is the sampling distribution of the sample mean X also a normal distribution ?
A.	Only when the sample size is at least 100.
B.	Only when the sample size is smaller than 30
C.	Always
D.	Only when the sample size is at least 30.
Answer» D. Only when the sample size is at least 30.