Two Independent Samples of Sizes 30 and 40 Are Randomly $\mu$

question 46

Multiple Choice

Two independent samples of sizes 30 and 40 are randomly selected from two populations to test the difference between the population means, µ $\mu$ ₂ - µ $\mu$ _1, where the population variances are unknown. Which of the following best describes the sampling distribution of the sample mean difference $\bar { x } _ { 1 } - \bar { x } _ { 2 }$ ?

• A) Normal.
• B) t-distributed with 68 degrees of freedom.
• C) Approximately normal.
• D) None of these choices are correct.

---

Definitions:

Ejecta

Material that is expelled or thrown out, especially as a result of volcanic eruption, meteorite impact, or other explosive events.

Sedimentary

Pertaining to rocks formed by the accumulation or deposition of mineral or organic particles at the Earth's surface, followed by compaction.

Sandstone

A sedimentary rock composed mainly of sand-sized minerals or rock grains.

Shale

A fine-grained sedimentary rock that can contain significant amounts of oil and natural gas.