In Testing the Difference Between Two Population Means Using Two $\bar { x } _ { 1 } - \bar { x } _ { 2 }$

question 88

Multiple Choice

In testing the difference between two population means using two independent samples, we use the pooled variance in estimating the standard error of the sampling distribution of the sample mean difference $\bar { x } _ { 1 } - \bar { x } _ { 2 }$ if:

• A)the sample sizes are both large.
• B)the populations are normal with equal variances.
• C)the populations are non-normal with unequal variances.
• D)All of these choices are true.

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Definitions:

Arachnids

A class of joint-legged invertebrate animals that includes spiders, scorpions, ticks, and mites.

Myriapods

A group of arthropods that includes centipedes and millipedes, characterized by having numerous legs.

Deuterostomes

A classification of animals characterized by the development of the anus from the first opening in the embryo, with the mouth forming later.

Echinoderms

A phylum of marine animals known for their radial symmetry and include starfish, sea urchins, and sea cucumbers.