Astronomy quiz question: star cluster with superigants

Astronomy 210 Quiz 5, spring semester 2012
Cuesta College, San Luis Obispo, CA

A star cluster containing supergiants would also have:
(A) white dwarfs.
(B) red dwarfs.
(C) medium-mass main sequence stars.
(D) type Ia supernovae.

Correct answer: (C)

Supergiants are massive stars that have ended their main-sequence lifetime, while medium-mass that have ended their main-sequence lifetime become giants, then planetary nebulae, then white dwarfs, which may explode as type Ia supernovae in a close binary system. Red dwarfs are low-mass main-sequence stars, which have an extremely long main-sequence lifetime. Since medium-mass stars have longer main-sequence lifetimes than massive stars, medium-mass stars must still be in their main-sequence stage when massive stars end their main-sequence lifetimes.

Section 30674
Exam code: quiz05nArf
(A) : 4 students
(B) : 2 students
(C) : 19 students
(D) : 7 students

"Success level": 64% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.33

Section 30676
Exam code: quiz05spH3
(A) : 9 students
(B) : 5 students
(C) : 20 students
(D) : 4 students

"Success level": 56% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.65