Final answer:
Shantiel's trip was 18 hours long, and she traveled 648 miles. The average speed is found by dividing the total distance by the total time, which gives us 36 miles per hour as the answer.
Step-by-step explanation:
To calculate Shantiel's average speed, we first need to determine the total time taken for the trip. She left at 9:00 a.m. and arrived at 3:00 a.m. the following day. The duration of her trip was therefore 18 hours. Next, we use the formula for average speed, which is:
Average Speed = Total Distance / Total Time
Substituting in the given values, we get:
Average Speed = 648 miles / 18 hours = 36 miles per hour
Therefore, option C, 36 miles per hour, is closest to Shantiel's average speed for her trip.