Answer: Elena's running speed = 5 miles per hour.
Step-by-step explanation:
Length of track = [tex]\dfrac14 \text{ mile}[/tex]
Time taken to complete one lap = [tex]\dfrac{1}{20}[/tex] of an hour.
Elena's running speed = [tex]\dfrac{Distance}{Time}[/tex]
[tex]=\dfrac{\dfrac14}{\dfrac1{20}}\text{ miles per hour}\\\\=\dfrac{20}{4}\text{ miles per hour}\\\\=5\text{ miles per hour}[/tex]
Hence, Elena's running speed = 5 miles per hour.
