40 out of my 108 students got the question right. The pop quiz had four different forms, all with different answers, but the professor did not announce this. Four students got the right answer for a form other than their own, so I presume that they were cheating off of someone who got it right.
So for a quiz worth 1.2% of their grade, 9% of students are willing to cheat if they don't think they will get caught.