Answer :
Given:
[tex]\begin{gathered} Q_1=1.5\times10^{-7}\text{ C} \\ Q_2=7.2\times10^{-5}\text{ C} \\ r=2.8\text{ m} \end{gathered}[/tex]The electrostatic force is given as,
[tex]F=\frac{KQ_1Q_2}{r^2}[/tex]Here, K is the electrostatic force constant.
Putting all values,
[tex]\begin{gathered} F=\frac{(9\times10^9\times1.5\times10^{-7}\times7.2\times10^{-5})^{}}{(2.8)^2} \\ =0.0124\text{ N} \end{gathered}[/tex]Therefore, the magnitude of the force between the charges is 0.0124 N.