You want to know the opinions of American school teachers about establishing a national test for high school graduation. You obtain a list of the members of the National Education Association (the largest teachers' union) and mail a questionnaire to 2500 teachers chosen at random from this list. In all 1347 teachers return the questionnaire. The intended population is ...

A) the 1347 teachers who mail back the questionnaire.

B) the 2500 teachers to whom you mailed the questionnaire.

C) all members of the National Education Association.

D) all American school teachers.

Answer: D) all American school teachers.

Step-by-step explanation:

In statistics, A population is a very large set of individuals or values that belong to a specified group established by researcher.

A sample is a subset of population that represents the entire population in research.

Given : We want to know the opinions of American school teachers about establishing a national test for high school graduation.

Clearly, by the above definition

Population = all American school teachers.

You obtain a list of the members of the National Education Association and mail a questionnaire to 2500 teachers chosen at random from this list.

sample = 2500 teachers chosen at random from this list.

Hence, the intended population is all American school teachers.

Thus, the correct answer is D) all American school teachers.