$2$ In the given circuit, $V_s=15V,R_i=200$ and $R_f=2k.$ What is the value of $V_{\text{o}\text{u}\text{t}}?$

A$)20$ V

B$)-20$ V

C$)15$ V

D$)-15$ V

E$)-0\mathrm{.}2$ V

$3$ A smart phone has a $3\mathrm{.}8$ Volt, Lithium Ion, $3100$ mAh battery. Its fully charged battery is completely