Two-sample t CI for μ₁ − μ₂ uses SE
- A
s/√(n₁ + n₂)
- Bcheck_circle
√(s₁²/n₁ + s₂²/n₂)
- C
(s₁ + s₂)/√n
- D
s_pooled
Explanation
Welch unpooled SE: each sample's SE squared, summed, square root.
Setting Up a Test for the Difference of Two Population Means
AP Statistics· difficulty 4/5
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