Answer
In the equation, $C\ =\ \frac{0.02{{P}_{1}}{{P}_{2}}}{{{d}^{2}}}$ , C varies jointly as ${{P}_{1}}$ and ${{P}_{2}}$ and inversely as the square of d.
Work Step by Step
Let us consider, $C\ =\ \frac{0.02{{P}_{1}}{{P}_{2}}}{{{d}^{2}}}$.
It can be seen that when ${{P}_{1}}$ and ${{P}_{2}}$ increase, C also increases or ${{P}_{1}}$ and ${{P}_{2}}$ decrease, S also decreases, and when d increases, C decreases or when d decreases, C increases. Thus here, 0.02 is the constant of proportionality.
Thus, in the equation $C\ =\ \frac{0.02{{P}_{1}}{{P}_{2}}}{{{d}^{2}}}$ , C varies jointly as ${{P}_{1}}$ and ${{P}_{2}}$ , and inversely as the square of d.
