Astronomy quiz question: moon phase, three weeks later?

Astronomy 210 Quiz 1, fall semester 2014
Cuesta College, San Luis Obispo, CA

The moon is in its waxing crescent phase. Which phase will the moon have three weeks later? Clearly circle your answer below.


Correct answer (highlight to unhide): (E)

The moon takes approximately four weeks (a "moonth") to go through its eight phases, such that it will take approximately one week to go through two phases, approximately two weeks to go through four phases, and approximately three weeks to go through six phases. Thus the moon in its waxing crescent phase will be in the waning crescent phase two weeks later.

Section 70158
Exam code: quiz01s7e8
(A) : 6 students
(B) : 3 students
(C) : 2 students
(D) : 7 students
(E) : 12 students
(F) : 6 students
(G) : 3 students
(H) : 5 students

Success level: 29% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.38