Astronomy quiz question: the most common nearby stars

Astronomy 210 Quiz 5, fall semester 2015
Cuesta College, San Luis Obispo, CA

If you surveyed only the nearest stars, the most common stars would be:
(A) red giants.
(B) red dwarfs.
(C) blue supergiants.
(D) sun-like stars.

Correct answer (highlight to unhide): (B)

The majority of nearby (and all stars in the Milky Way) are red dwarfs and white dwarfs, while the most common stars visible to the naked eye are the distant but brighter and hotter massive main-sequence stars, giants and supergiants.

The prevalence of these unremarkable, dim stars compared to the less-common, but brighter massive main-sequence stars, supergiants, and giants is analogous to a "high school cafeteria" model, where the few glamorous, high-profile students would be noticeable from at a distance, while the multitude of average students throughout the room are ignored.

Section 70158
Exam code: quiz05s3T1
(A) : 7 students
(B) : 10 students
(C) : 8 students
(D) : 15 students

Success level: 30% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.34

Section 70160
Exam code: quiz05ne7A
(A) : 3 students
(B) : 9 students
(C) : 5 students
(D) : 5 students

Success level: 40% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.43