$7\mathrm{.}32$ An exponential voltage decay $v(t)=v(0)e^{-\frac{t}{}}$ is observed with an oscilloscope. If it is found that $v(1s)=12\mathrm{.}28$ V and $v(7s)=3\mathrm{.}7V,($a$)$ find $v(0)$ and $,$ and $($b$)$ predict $v(10s).$

$7\mathrm{.}33$ If it is found that an exponential current $i(t)=i(0)e^{-\frac{t}{}}$ takes $5\mathrm{.}545$ ms to decay from $8$ mA to $2$ mA $,$ how long does it take to decay from $6$ mA to $4$ mA $?$ From $9$ mA to $1$ mA $?$