Ms. Spilker rode her bike at a rate of 30 miles/2 hours = <<30/2=15>>15 miles/hour.
Therefore, in 0.5 hours, she would have ridden 15 miles/hour * 0.5 hours = <<15*0.5=7.5>>7.5 miles.
So, she rode her bike 7.5 miles in 0.5 hours.
Therefore, in 0.5 hours, she would have ridden 15 miles/hour * 0.5 hours = <<15*0.5=7.5>>7.5 miles.
So, she rode her bike 7.5 miles in 0.5 hours.
Average speed is calculated by dividing the distance traveled by the time taken.
Given information:
Distance = 30 miles
Time = 2 hours
Average speed = Distance / Time
Average speed = 30 miles / 2 hours
Average speed = 15 miles per hour
Now, we can use the average speed to find the distance traveled in 0.5 hours.
Distance = Speed × Time
Distance = 15 miles per hour × 0.5 hours
Distance = 7.5 miles
Therefore, Ms. Spilker rode her bike 7.5 miles in 0.5 hours.
Let's call the distance Ms. Spilker rode in 0.5 hours "x". The proportion can be set up as:
30 miles / 2 hours = x miles / 0.5 hours
To solve the proportion, we can cross multiply:
2 hours * x miles = 30 miles * 0.5 hours
2x = 15
Divide both sides of the equation by 2:
x = 7.5 miles
Therefore, Ms. Spilker rode her bike 7.5 miles in 0.5 hours. So, the correct response is: 7.5 miles.