Final answer:
Rachel rode her bike for less than 9 miles per week.
Step-by-step explanation:
To determine if Rachel rode her bike for less than 9 miles per week, we can divide the total distance she rode (51.12 miles) by the number of weeks (6). The calculation is:
51.12 miles ÷ 6 weeks = 8.52 miles per week
Therefore, Rachel did ride her bike for less than 9 miles per week. The correct answer is D - Yes, because 51.12 divided by 6 is 8.52.