[tex]\begin{gathered} 1) \\ f_1=0.6megahertz=0.6x10^6hertz=600000hertz \\ f_2=354kilohertz=354x10^3hertz=354000hertz \\ difference=600000hertz-354000hertz \\ difference=246000hertz \\ \text{The difference is }246000hertz \\ \\ 2) \\ l_b=l_e-l_c \\ l_e=2.93\text{ }miliamperes=2.93x10^3microamperes=2930\text{ microamperes} \\ l_c=2.87\text{ miliamperes}=2.87x10^3\text{ microamperes=2870 microamperes} \\ l_b=2930\text{ microamperes}-\text{2870 microamperes} \\ l_b=60\text{microamperes} \\ The\text{ }base\text{ current is }60\text{microamperes} \\ \\ 3)\text{ } \\ \text{ERM}_{}=E_P\text{ x 0.707} \\ E_P\text{ =}1.75\text{ volts}=1.75x10^3\text{ milivolts}=1750\text{ milivolts} \\ \text{ERM}_{}=1750\text{ milivolts x 0.707} \\ \text{ERM}=1237.25\text{ milivolts} \\ \text{The ERM is }1237.25\text{ milivolts} \\ \\ 4) \\ 675meters=675x10^{-3}kilometers=0.675\text{ kilometers} \\ additional\text{ =}0.75\text{ kilometers -0.675 kilometers} \\ additional\text{ =0.075 kilometers} \\ \text{They n}eed\text{ 0.075 kilometers} \end{gathered}[/tex]