Answer:
The rate of change is 12ft/s
Explanation:
Given
![h(t) = -16t^2 + 20t](https://img.qammunity.org/2022/formulas/mathematics/high-school/9iai8id0yjcdwnyzqgp6ey1es4ddtcdwuv.png)
Required
Rate of change from when she jumps till 1/2s
The time she jumps is represented as: t = 0
So, calculate h(0)
![h(t) = -16t^2 + 20t](https://img.qammunity.org/2022/formulas/mathematics/high-school/9iai8id0yjcdwnyzqgp6ey1es4ddtcdwuv.png)
![h(0) = -16 * 0^2 + 20 * 0 = 0](https://img.qammunity.org/2022/formulas/mathematics/high-school/ev4tuza16vrw4yxirmyvzyquo7qrlsodka.png)
At t = 1/2
![h(t) = -16t^2 + 20t](https://img.qammunity.org/2022/formulas/mathematics/high-school/9iai8id0yjcdwnyzqgp6ey1es4ddtcdwuv.png)
![h(1/2) = -16 * 1/2^2 + 20 * 1/2 = 6](https://img.qammunity.org/2022/formulas/mathematics/high-school/ysj9em10fdol73v8iflrrd96lknw8xssi1.png)
Rate of change is calculated as:
![Rate = (f(b) - f(a))/(b - a)](https://img.qammunity.org/2022/formulas/mathematics/college/owrxn79d3y26675kjet56m427ktjv6w031.png)
In this case:
![Rate = (h(b) - h(a))/(b - a)](https://img.qammunity.org/2022/formulas/mathematics/high-school/210ns1i35i2wzhr0i0xixst7mpgt3rvu8h.png)
Where
![(a,b) = (0,1/2)](https://img.qammunity.org/2022/formulas/mathematics/high-school/xij8b2ckbql87za6d3inyyijyaa74rse9y.png)
So, we have:
![Rate = (h(b) - h(a))/(b - a)](https://img.qammunity.org/2022/formulas/mathematics/high-school/210ns1i35i2wzhr0i0xixst7mpgt3rvu8h.png)
![Rate = (h(1/2) - h(0))/(1/2 - 0)](https://img.qammunity.org/2022/formulas/mathematics/high-school/r28d9wwbaq0sqnwvutil3xbupejc1a7dq0.png)
![Rate = (6 - 0)/(1/2 - 0)](https://img.qammunity.org/2022/formulas/mathematics/high-school/lqmmehkk05j2dga36al8ggjeqd2rieivab.png)
![Rate = (6)/(1/2)](https://img.qammunity.org/2022/formulas/mathematics/high-school/jfpd4iqncy151eo9eu8y40grt1jyglaawz.png)
![Rate =12](https://img.qammunity.org/2022/formulas/mathematics/high-school/ql5th8wbzd3zig2gt72im3fkdlvny2d9ir.png)
The rate of change is 12ft/s