Answer: Average speed is given by the formula:
speed = distance ÷ time
Given that Darlene rode her bike 8 2/5 miles in 3/4 of an hour. We need to convert the mixed number 8 2/5 to an improper fraction.
8 2/5 = (8 x 5 + 2) / 5 = 42/5
So, Darlene rode her bike a distance of 42/5 miles in a time of 3/4 hours.
Substitute speed = distance ÷ time
speed = (42/5) ÷ (3/4)
To divide by a fraction, we invert and multiply:
speed = (42/5) x (4/3)
speed = 56/5
So, Darlene's average speed was 56/5 miles per hour (mph).
To simplify this fraction, we can divide both the numerator and denominator by 1:
speed = 11/1