Question 8 • CA-Statistics and Probability B
A difference in sample means is suitable for probability calculations when its sampling distribution is approximately Normal. Large samples (usually at least 30) make sample means approximately Normal even if the population shapes are unknown or skewed; a sample from a Normal population has a Normal mean for any sample size. Thus A and E qualify because both samples are large, and B qualifies because n₁ = 50 is large while population 2 is Normal. D, C, and F have small samples from skewed populations, so Normality is not assured.
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