To determine Shayla's average speed while running the last half mile, we need to follow these steps:
1. Understand the Problem:
- Distance Shayla ran: 0.5 miles
- Time taken to run this distance: 4 minutes
2. Convert Time from Minutes to Hours:
Since speed needs to be expressed in miles per hour, we'll convert the time from minutes to hours.
- There are 60 minutes in an hour. So, time in hours is calculated as follows:
[tex]\[
\text{Time in hours} = \frac{\text{Time in minutes}}{60} = \frac{4}{60} = 0.0667 \text{ hours}
\][/tex]
3. Calculate Average Speed:
Average speed is given by the formula:
[tex]\[
\text{Average Speed} = \frac{\text{Distance}}{\text{Time}}
\][/tex]
Plugging in the values we have:
[tex]\[
\text{Average Speed} = \frac{0.5 \text{ miles}}{0.0667 \text{ hours}} = 7.5 \text{ mph}
\][/tex]
Shayla's average speed while running was 7.5 miles per hour. Therefore, the correct answer is:
B. 7.5 mph
