Answer:
42.5W
Step-by-step explanation:
To solve this problem we must go back to the calculations of a weighted average based on the time elapsed thus,
![Power_(avg) = (P_1(t_1)+P_2(t_2))/(t_1+t_2)](https://img.qammunity.org/2020/formulas/physics/college/hmvqa42kktrar7y1v9g7r9xnc52wv2gefh.png)
We need to calculate the average power dissipated by the 800\Omega resistor.
Our values are given by:
![P(t)=60 W, 0\leq t<5.0s](https://img.qammunity.org/2020/formulas/physics/college/mpn7c59a5iw4j1dpiuk3d2kgftnbxg631b.png)
![P(t)=25 W, 5.0\leq t<10s](https://img.qammunity.org/2020/formulas/physics/college/u6tkeg2ww8b6jdjexpqgqveohu4ts4pge4.png)
Aplying the values to the equation we have:
![Power_(avg) = (P_1(t_1)+P_2(t_2))/(t_1+t_2)](https://img.qammunity.org/2020/formulas/physics/college/hmvqa42kktrar7y1v9g7r9xnc52wv2gefh.png)
![Power_(avg) = (60(5-0)+25(10-5))/((5-0)+(10-5))](https://img.qammunity.org/2020/formulas/physics/college/nqaicqkvj26r734n0fgpimq0azkbuqndw6.png)
![Power_(avg) = 42.5W](https://img.qammunity.org/2020/formulas/physics/college/3phg28v71iin0z77ajn60gmos5vtgmvzb3.png)