Physics quiz question: cheetah running speed

Physics 205A Quiz 1, fall semester 2013
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 1.25

Recent research on tracking the running speeds of cheetahs hunting in the wild[*] reported a top recorded speed of 25.9 m/s. One mile is equivalent to 1.609344 km. The top speed of this cheetah in miles per minute is:
(A) 0.966 mi/min.
(B) 1.04 mi/min.
(C) 11.6 mi/min.
(D) 695 mi/min.

[*] A. M. Wilson, J. C. Lowe, K. Roskilly, P. E. Hudson, K. A. Golabek and J. W. McNutt, "Locomotion Dynamics of Hunting in Wild Cheetahs," Nature vol. 498 (13 June 2013), pp. 185–189.

Correct answer (highlight to unhide): (A)

Setting up conversion factors such that unwanted units cancel (m, s, km) while desired units remain (mi, min):

25.9 m/s × ((1 km)/(1,000 m)) × ((1 mi)/(1.609344 km)) × ((60 s)/(1 min)) = 0.9656108327 mi/min,

or to three significant figures, 0.966 mi/min.

Sections 70854, 70855, 73320
Exam code: quiz01cH3E
(A) : 63 students
(B) : 9 students
(C) : 3 students
(D) : 1 student

Success level: 83%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.50