Use z (not t) when
- A
Always
- B
n < 30 always
- Ccheck_circle
σ is known
- D
σ is unknown
Explanation
Most real cases use t because σ is rarely known.
AP Statistics· difficulty 3/5
Use z (not t) when
Always
n < 30 always
σ is known
σ is unknown
Explanation
Most real cases use t because σ is rarely known.
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