Respuesta :
Well, if Julia finishes a 20-mile ride in 1.2 hours, her speed is 20/1.2, or 16.667 miles per hour. Katie's speed is 20/1.6, or 12.5 miles per hour. So Julia is 16.667-12.5 miles per hour faster than Katie, or 4.167.
We know that,[tex]speed = \frac{distance}{time}[/tex]
Julia can finish a 20-mile bike ride in 1.2 hours.
The distance Julia travels is 20 miles and the time she takes is 1.2 hours.
So, Julia's speed = [tex]\frac{20}{1.2}[/tex] = 16.67 mph
Katie can finish the same bike ride in 1.6 hours.
The distance Katie travels is 20 miles and the time she takes is 1.6 hours.
So, Katie's speed = [tex]\frac{20}{1.6}[/tex] = 12.5 mph
Now, to find how much faster Julia rides than Katie we subtract Katie's speed from Julia's speed.
So, 16.67 mph - 12.5 mph = 4.17 mph = 4.2 mph (approximately)
Thus, Julia rides 4.2 mph faster than Katie.