That is a fairly large temperature drop. Even though it is within the fermentation range, it's quite possible the yeast went dormant. Still it could be done & checking the gravity is the only way to be certain.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk