Using proportions, it is found that they had traveled 624 miles when Christopher fell asleep.
A proportion is a fraction of a total amount, and the measures are related using a rule of three.
In this problem, Christopher fell asleep at a distance that is 65% of 960 miles, hence the distance they had traveled is given by:
D = 0.65 x 960 miles = 624 miles.
More can be learned about proportions at https://brainly.com/question/24372153
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