Final answer:
Jenny will be practicing by running 24 miles during Week 3.
Step-by-step explanation:
To determine the week in which Jenny will be practicing by running 24 miles, we need to add up the distances she runs in each week until we reach 24 miles.
In Week 1, she runs 1.5 miles every other day, which means she runs 1.5 miles * 3 days = 4.5 miles in a week.
In Week 2, she runs 4 miles every other day, which means she runs 4 miles * 3 days = 12 miles in a week.
In Week 3, she runs 6.5 miles every other day, which means she runs 6.5 miles * 3 days = 19.5 miles in a week.
Adding up the distances from each week, we have 4.5 + 12 + 19.5 = 36 miles.
Since Jenny reaches 24 miles during Week 3, the answer is Week 3.