Answer:

Step-by-step explanation:
To find the average velocity of Shelby's little sister, we can use the formula for average velocity:
![\[\text{Average Velocity} = \frac{\text{Displacement}}{\text{Time}}\]](https://img.qammunity.org/2024/formulas/chemistry/high-school/mt4j0sibyfs84d8iew9nsl603jfp46jktb.png)
In this case, the displacement is
(the distance from where Shelby started to where the race ends), and the time taken is
,
.
So, the average velocity would be:
![\[\text{Average Velocity} = \frac{15 \, \text{m}}{5 \, \text{s}} = 3 \, \text{m/s}\]](https://img.qammunity.org/2024/formulas/chemistry/high-school/l17f5rozmq6g2ncn1puqsntnxfxdm4w8dh.png)
Rounded to the nearest whole number, the average velocity of Shelby's little sister is
.