$[30$ points$]$ DVFS is a widely used approach for energy saving in today's computer systems.

Assume that a system needs to run two real$-$time applications within $30$ seconds as shown

in the table below. Show the most energy$-$efficient schedule of the two applications.

Compare its average power consumption $($within $30$ seconds$)$ with the schedule that

finishes each application at the earliest possible time. Assume that the system consumes

zero power during idle time, and the supply voltage is proportional to the clock rate.