Two Independent Samples of Sizes 35 and 40 Are Randomly $\mu _ { 1 } - \mu _ { 2 }$

question 9

Multiple Choice

Two independent samples of sizes 35 and 40 are randomly selected from two normally distributed populations. Assume that the population variances are unknown but equal. In order to test the difference between the population means, $\mu _ { 1 } - \mu _ { 2 }$ , the sampling distribution of the sample mean difference, $\bar { x } _ { 1 } - \bar { x } _ { 2 }$ , is:

• A) normally distributed.
• B) t-distributed with 75 degrees of freedom.
• C) t-distributed with 73 degrees of freedom.
• D) F-distributed with 34 and 39 degrees of freedom.

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Definitions:

Chordates

A large phylum of animals that includes all vertebrates as well as several closely related invertebrates, characterized by the presence of a notochord at some stage of their development.

Monotremes

Egg-laying mammals, such as the platypus and echidna, representing a unique branch of the mammalian tree.

Parthenogenesis

The development of an unfertilized egg into an adult organism; common among honeybees, wasps, and certain other arthropods.

Lay Eggs

The act of depositing eggs by a female organism, as a means of reproduction.