To find out how much time, on average, it takes Erika less per mile compared to Rita, we need to follow these steps:
1. Calculate the average time taken by Erika over the five days:
- Erika's times: 20, 21.5, 22.75, 23.25, 20.25
- Sum of Erika's times: 20 + 21.5 + 22.75 + 23.25 + 20.25 = 107.75
- Number of days: 5
- Average time for Erika: 107.75 / 5 = 21.55 minutes
2. Calculate the average time taken by Rita over the five days:
- Rita's times: 21.25, 24.75, 23, 23, 20.75
- Sum of Rita's times: 21.25 + 24.75 + 23 + 23 + 20.75 = 112.75
- Number of days: 5
- Average time for Rita: 112.75 / 5 = 22.55 minutes
3. Determine the difference between Rita's and Erika's average times:
- Difference: 22.55 - 21.55 = 1.0 minute
So, on average, it takes Erika about 1.0 minute(s) per mile less than Rita.
The answer is: 1.0