What is the equivalent of 42 min. 48 sec. in arc units?

Correct Answer: Option A — 10°42'

Converting time to arc requires applying the Earth's rotational rate of 15 degrees per hour, 15 arcminutes per minute, and 15 arcseconds per second. Multiplying 42 minutes by 15 gives 630 arcminutes, and 48 seconds gives 720 arcseconds. Dividing by 60 converts units, resulting precisely in 10 degrees 42 minutes per Bowditch standards.